本页面介绍如何使用数据操纵语言 (DML) 语句插入、更新和删除 Spanner 数据。您可以使用客户端库、Google Cloud 控制台和 gcloud 命令行工具来运行 DML 语句。您可以使用客户端库和 gcloud 命令行工具来运行分区 DML 语句
如需查看完整的 DML 语法参考，请参阅 GoogleSQL 方言数据库的数据操纵语言语法或 PostgreSQL 方言数据库的 PostgreSQL 数据操纵语言
使用 DML
DML 支持在 Google Cloud 控制台、Google Cloud CLI 和客户端库中使用 INSERT、UPDATE 和 DELETE 语句。
锁定
在读写事务中执行 DML 语句。当 Spanner 读取数据时，它会在您读取的有限部分行范围上获取共享读取锁定。具体而言，它仅会对您访问的列获取这些锁定。锁可以包含不符合 WHERE 子句过滤条件的数据。
当 Spanner 使用 DML 语句修改数据时，它会对您要修改的特定数据获取独占锁定。此外，它还会采用与读取数据时相同的方式获取共享锁定。如果您的请求包含较大的行范围或整个表，则共享锁定可能会阻止其他事务并行进行。
为了尽可能高效地修改数据，请使用 WHERE 子句，以使 Spanner 只读取必要的行。您可以通过按主键进行过滤或按二级索引的键进行过滤来实现此目标。WHERE 子句限制了共享锁定的范围，使 Spanner 能够更高效地处理更新。
例如，假设 Singers 表中的某位音乐人更改了其名字，则您需要在您的数据库中更新该名字。您可以执行以下 DML 语句，但它会强制 Spanner 扫描整个表并获取覆盖整个表的共享锁。因此，Spanner 必须读取更多不必要的数据，并且并发事务无法并行修改数据：
-- ANTI-PATTERN: SENDING AN UPDATE WITHOUT THE PRIMARY KEY COLUMN
-- IN THE WHERE CLAUSE
UPDATE Singers SET FirstName = "Marcel"
WHERE FirstName = "Marc" AND LastName = "Richards";
为使该更新更加高效，请在 WHERE 子句中添加 SingerId 列。SingerId 列是 Singers 表的唯一主键列：
-- ANTI-PATTERN: SENDING AN UPDATE THAT MUST SCAN THE ENTIRE TABLE
UPDATE Singers SET FirstName = "Marcel"
WHERE FirstName = "Marc" AND LastName = "Richards"
如果 FirstName 或 LastName 上没有索引，您需要扫描整个表来查找目标歌手。如果您不想通过添加二级索引来提高更新效率，请在 WHERE 子句中添加 SingerId 列。
SingerId 列是 Singers 表的唯一主键列。如需找到它，请在更新事务之前在单独的只读事务中运行 SELECT：
SELECT SingerId
FROM Singers
WHERE FirstName = "Marc" AND LastName = "Richards"
-- Recommended: Including a seekable filter in the where clause
UPDATE Singers SET FirstName = "Marcel"
WHERE SingerId = 1;
并发
Spanner 按顺序执行事务中的所有 SQL 语句（SELECT、INSERT、UPDATE 和 DELETE）。这些语句不是同时执行的。唯一的例外是 Spanner 可能会同时执行多个 SELECT 语句，因为它们是只读操作。
事务限制
包含 DML 语句的事务与任何其他事务具有相同的限制。如果您进行大规模更改，请考虑使用分区 DML。
如果事务中的 DML 语句导致超过 80,000 项变更，则致使该事务超出限制的 DML 语句将返回
BadUsage错误，并显示有关变更过多的消息。如果事务中的 DML 语句导致事务大于 100 MB，则致使该事务超出限制的 DML 语句将返回
BadUsage错误，并显示指明事务超出大小限制的消息。
使用 DML 执行的变更不会返回给客户端。这些变更会在提交时合并到提交请求中，并计入最大大小限制。即使您发送的提交请求的很小，该事务仍可能超过允许的大小限制。
在 Google Cloud 控制台中运行语句
请按照以下步骤在 Google Cloud 控制台中执行 DML 语句。
转到 Spanner 实例页面。
在工具栏的下拉列表中选择您的项目。
点击包含您的数据库的实例的名称，以转到实例详情页面。
在概览标签页中，点击数据库的名称。此时将显示数据库详细信息页面。
点击 Spanner Studio。
输入 DML 语句。例如，以下语句向
Singers表中添加一个新行。INSERT Singers (SingerId, FirstName, LastName) VALUES (1, 'Marc', 'Richards')点击运行查询。 Google Cloud 控制台会显示结果。
使用 Google Cloud CLI 执行语句
如需执行 DML 语句，请使用 gcloud spanner databases execute-sql 命令。以下示例向 Singers 表中添加一个新行。
gcloud spanner databases execute-sql example-db --instance=test-instance \
--sql="INSERT Singers (SingerId, FirstName, LastName) VALUES (1, 'Marc', 'Richards')"
使用客户端库修改数据
要使用客户端库执行 DML 语句，请执行以下操作：
- 创建一个读写事务。
- 调用客户端库方法执行 DML 并传入 DML 语句。
- 使用 DML 执行方法的返回值来获取插入、更新或删除的行数。
以下代码示例在 Singers 表中插入一个新行。
C++
使用 ExecuteDml() 函数来执行 DML 语句。
void DmlStandardInsert(google::cloud::spanner::Client client) {
using ::google::cloud::StatusOr;
namespace spanner = ::google::cloud::spanner;
std::int64_t rows_inserted;
auto commit_result = client.Commit(
[&client, &rows_inserted](
spanner::Transaction txn) -> StatusOr<spanner::Mutations> {
auto insert = client.ExecuteDml(
std::move(txn),
spanner::SqlStatement(
"INSERT INTO Singers (SingerId, FirstName, LastName)"
" VALUES (10, 'Virginia', 'Watson')"));
if (!insert) return std::move(insert).status();
rows_inserted = insert->RowsModified();
return spanner::Mutations{};
});
if (!commit_result) throw std::move(commit_result).status();
std::cout << "Rows inserted: " << rows_inserted;
std::cout << "Insert was successful [spanner_dml_standard_insert]\n";
}C#
使用 ExecuteNonQueryAsync() 方法来执行 DML 语句。
using Google.Cloud.Spanner.Data;
using System;
using System.Threading.Tasks;
public class InsertUsingDmlCoreAsyncSample
{
public async Task<int> InsertUsingDmlCoreAsync(string projectId, string instanceId, string databaseId)
{
string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";
using var connection = new SpannerConnection(connectionString);
await connection.OpenAsync();
using var cmd = connection.CreateDmlCommand("INSERT Singers (SingerId, FirstName, LastName) VALUES (10, 'Virginia', 'Watson')");
int rowCount = await cmd.ExecuteNonQueryAsync();
Console.WriteLine($"{rowCount} row(s) inserted...");
return rowCount;
}
}Go
使用 Update() 方法来执行 DML 语句。
import (
"context"
"fmt"
"io"
"cloud.google.com/go/spanner"
)
func insertUsingDML(w io.Writer, db string) error {
ctx := context.Background()
client, err := spanner.NewClient(ctx, db)
if err != nil {
return err
}
defer client.Close()
_, err = client.ReadWriteTransaction(ctx, func(ctx context.Context, txn *spanner.ReadWriteTransaction) error {
stmt := spanner.Statement{
SQL: `INSERT Singers (SingerId, FirstName, LastName)
VALUES (10, 'Virginia', 'Watson')`,
}
rowCount, err := txn.Update(ctx, stmt)
if err != nil {
return err
}
fmt.Fprintf(w, "%d record(s) inserted.\n", rowCount)
return nil
})
return err
}
Java
使用 executeUpdate() 方法来执行 DML 语句。
static void insertUsingDml(DatabaseClient dbClient) {
dbClient
.readWriteTransaction()
.run(transaction -> {
String sql =
"INSERT INTO Singers (SingerId, FirstName, LastName) "
+ " VALUES (10, 'Virginia', 'Watson')";
long rowCount = transaction.executeUpdate(Statement.of(sql));
System.out.printf("%d record inserted.\n", rowCount);
return null;
});
}Node.js
使用 runUpdate() 方法来执行 DML 语句。
// Imports the Google Cloud client library
const {Spanner} = require('@google-cloud/spanner');
/**
* TODO(developer): Uncomment the following lines before running the sample.
*/
// const projectId = 'my-project-id';
// const instanceId = 'my-instance';
// const databaseId = 'my-database';
// Creates a client
const spanner = new Spanner({
projectId: projectId,
});
// Gets a reference to a Cloud Spanner instance and database
const instance = spanner.instance(instanceId);
const database = instance.database(databaseId);
database.runTransaction(async (err, transaction) => {
if (err) {
console.error(err);
return;
}
try {
const [rowCount] = await transaction.runUpdate({
sql: 'INSERT Singers (SingerId, FirstName, LastName) VALUES (10, @firstName, @lastName)',
params: {
firstName: 'Virginia',
lastName: 'Watson',
},
});
console.log(
`Successfully inserted ${rowCount} record into the Singers table.`
);
await transaction.commit();
} catch (err) {
console.error('ERROR:', err);
} finally {
// Close the database when finished.
database.close();
}
});PHP
使用 executeUpdate() 方法来执行 DML 语句。
use Google\Cloud\Spanner\SpannerClient;
use Google\Cloud\Spanner\Transaction;
/**
* Inserts sample data into the given database with a DML statement.
*
* The database and table must already exist and can be created using
* `create_database`.
* Example:
* ```
* insert_data($instanceId, $databaseId);
* ```
*
* @param string $instanceId The Spanner instance ID.
* @param string $databaseId The Spanner database ID.
*/
function insert_data_with_dml(string $instanceId, string $databaseId): void
{
$spanner = new SpannerClient();
$instance = $spanner->instance($instanceId);
$database = $instance->database($databaseId);
$database->runTransaction(function (Transaction $t) {
$rowCount = $t->executeUpdate(
'INSERT Singers (SingerId, FirstName, LastName) '
. " VALUES (10, 'Virginia', 'Watson')");
$t->commit();
printf('Inserted %d row(s).' . PHP_EOL, $rowCount);
});
}Python
使用 execute_update() 方法来执行 DML 语句。
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
def insert_singers(transaction):
row_ct = transaction.execute_update(
"INSERT INTO Singers (SingerId, FirstName, LastName) "
" VALUES (10, 'Virginia', 'Watson')"
)
print("{} record(s) inserted.".format(row_ct))
database.run_in_transaction(insert_singers)Ruby
使用 execute_update() 方法来执行 DML 语句。
# project_id = "Your Google Cloud project ID"
# instance_id = "Your Spanner instance ID"
# database_id = "Your Spanner database ID"
require "google/cloud/spanner"
spanner = Google::Cloud::Spanner.new project: project_id
client = spanner.client instance_id, database_id
row_count = 0
client.transaction do |transaction|
row_count = transaction.execute_update(
"INSERT INTO Singers (SingerId, FirstName, LastName) VALUES (10, 'Virginia', 'Watson')"
)
end
puts "#{row_count} record inserted."以下代码示例根据 WHERE 子句更新 Albums 表的 MarketingBudget 列。
C++
void DmlStandardUpdate(google::cloud::spanner::Client client) {
using ::google::cloud::StatusOr;
namespace spanner = ::google::cloud::spanner;
auto commit_result = client.Commit(
[&client](spanner::Transaction txn) -> StatusOr<spanner::Mutations> {
auto update = client.ExecuteDml(
std::move(txn),
spanner::SqlStatement(
"UPDATE Albums SET MarketingBudget = MarketingBudget * 2"
" WHERE SingerId = 1 AND AlbumId = 1"));
if (!update) return std::move(update).status();
return spanner::Mutations{};
});
if (!commit_result) throw std::move(commit_result).status();
std::cout << "Update was successful [spanner_dml_standard_update]\n";
}C#
using Google.Cloud.Spanner.Data;
using System;
using System.Threading.Tasks;
public class UpdateUsingDmlCoreAsyncSample
{
public async Task<int> UpdateUsingDmlCoreAsync(string projectId, string instanceId, string databaseId)
{
string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";
using var connection = new SpannerConnection(connectionString);
await connection.OpenAsync();
using var cmd = connection.CreateDmlCommand("UPDATE Albums SET MarketingBudget = MarketingBudget * 2 WHERE SingerId = 1 and AlbumId = 1");
int rowCount = await cmd.ExecuteNonQueryAsync();
Console.WriteLine($"{rowCount} row(s) updated...");
return rowCount;
}
}Go
import (
"context"
"fmt"
"io"
"cloud.google.com/go/spanner"
)
func updateUsingDML(w io.Writer, db string) error {
ctx := context.Background()
client, err := spanner.NewClient(ctx, db)
if err != nil {
return err
}
defer client.Close()
_, err = client.ReadWriteTransaction(ctx, func(ctx context.Context, txn *spanner.ReadWriteTransaction) error {
stmt := spanner.Statement{
SQL: `UPDATE Albums
SET MarketingBudget = MarketingBudget * 2
WHERE SingerId = 1 and AlbumId = 1`,
}
rowCount, err := txn.Update(ctx, stmt)
if err != nil {
return err
}
fmt.Fprintf(w, "%d record(s) updated.\n", rowCount)
return nil
})
return err
}
Java
static void updateUsingDml(DatabaseClient dbClient) {
dbClient
.readWriteTransaction()
.run(transaction -> {
String sql =
"UPDATE Albums "
+ "SET MarketingBudget = MarketingBudget * 2 "
+ "WHERE SingerId = 1 and AlbumId = 1";
long rowCount = transaction.executeUpdate(Statement.of(sql));
System.out.printf("%d record updated.\n", rowCount);
return null;
});
}Node.js
// Imports the Google Cloud client library
const {Spanner} = require('@google-cloud/spanner');
/**
* TODO(developer): Uncomment the following lines before running the sample.
*/
// const projectId = 'my-project-id';
// const instanceId = 'my-instance';
// const databaseId = 'my-database';
// Creates a client
const spanner = new Spanner({
projectId: projectId,
});
// Gets a reference to a Cloud Spanner instance and database
const instance = spanner.instance(instanceId);
const database = instance.database(databaseId);
database.runTransaction(async (err, transaction) => {
if (err) {
console.error(err);
return;
}
try {
const [rowCount] = await transaction.runUpdate({
sql: `UPDATE Albums SET MarketingBudget = MarketingBudget * 2
WHERE SingerId = 1 and AlbumId = 1`,
});
console.log(`Successfully updated ${rowCount} record.`);
await transaction.commit();
} catch (err) {
console.error('ERROR:', err);
} finally {
// Close the database when finished.
database.close();
}
});PHP
use Google\Cloud\Spanner\SpannerClient;
use Google\Cloud\Spanner\Transaction;
/**
* Updates sample data in the database with a DML statement.
*
* This requires the `MarketingBudget` column which must be created before
* running this sample. You can add the column by running the `add_column`
* sample or by running this DDL statement against your database:
*
* ALTER TABLE Albums ADD COLUMN MarketingBudget INT64
*
* Example:
* ```
* update_data($instanceId, $databaseId);
* ```
*
* @param string $instanceId The Spanner instance ID.
* @param string $databaseId The Spanner database ID.
*/
function update_data_with_dml(string $instanceId, string $databaseId): void
{
$spanner = new SpannerClient();
$instance = $spanner->instance($instanceId);
$database = $instance->database($databaseId);
$database->runTransaction(function (Transaction $t) {
$rowCount = $t->executeUpdate(
'UPDATE Albums '
. 'SET MarketingBudget = MarketingBudget * 2 '
. 'WHERE SingerId = 1 and AlbumId = 1');
$t->commit();
printf('Updated %d row(s).' . PHP_EOL, $rowCount);
});
}Python
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
def update_albums(transaction):
row_ct = transaction.execute_update(
"UPDATE Albums "
"SET MarketingBudget = MarketingBudget * 2 "
"WHERE SingerId = 1 and AlbumId = 1"
)
print("{} record(s) updated.".format(row_ct))
database.run_in_transaction(update_albums)Ruby
# project_id = "Your Google Cloud project ID"
# instance_id = "Your Spanner instance ID"
# database_id = "Your Spanner database ID"
require "google/cloud/spanner"
spanner = Google::Cloud::Spanner.new project: project_id
client = spanner.client instance_id, database_id
row_count = 0
client.transaction do |transaction|
row_count = transaction.execute_update(
"UPDATE Albums
SET MarketingBudget = MarketingBudget * 2
WHERE SingerId = 1 and AlbumId = 1"
)
end
puts "#{row_count} record updated."以下代码示例删除 FirstName 列为 Alice 的 Singers 表中的所有行。
C++
void DmlStandardDelete(google::cloud::spanner::Client client) {
using ::google::cloud::StatusOr;
namespace spanner = ::google::cloud::spanner;
auto commit_result = client.Commit([&client](spanner::Transaction txn)
-> StatusOr<spanner::Mutations> {
auto dele = client.ExecuteDml(
std::move(txn),
spanner::SqlStatement("DELETE FROM Singers WHERE FirstName = 'Alice'"));
if (!dele) return std::move(dele).status();
return spanner::Mutations{};
});
if (!commit_result) throw std::move(commit_result).status();
std::cout << "Delete was successful [spanner_dml_standard_delete]\n";
}C#
using Google.Cloud.Spanner.Data;
using System;
using System.Threading.Tasks;
public class DeleteUsingDmlCoreAsyncSample
{
public async Task<int> DeleteUsingDmlCoreAsync(string projectId, string instanceId, string databaseId)
{
string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";
using var connection = new SpannerConnection(connectionString);
await connection.OpenAsync();
using var cmd = connection.CreateDmlCommand("DELETE FROM Singers WHERE FirstName = 'Alice'");
int rowCount = await cmd.ExecuteNonQueryAsync();
Console.WriteLine($"{rowCount} row(s) deleted...");
return rowCount;
}
}Go
import (
"context"
"fmt"
"io"
"cloud.google.com/go/spanner"
)
func deleteUsingDML(w io.Writer, db string) error {
ctx := context.Background()
client, err := spanner.NewClient(ctx, db)
if err != nil {
return err
}
defer client.Close()
_, err = client.ReadWriteTransaction(ctx, func(ctx context.Context, txn *spanner.ReadWriteTransaction) error {
stmt := spanner.Statement{SQL: `DELETE FROM Singers WHERE FirstName = 'Alice'`}
rowCount, err := txn.Update(ctx, stmt)
if err != nil {
return err
}
fmt.Fprintf(w, "%d record(s) deleted.\n", rowCount)
return nil
})
return err
}
Java
static void deleteUsingDml(DatabaseClient dbClient) {
dbClient
.readWriteTransaction()
.run(transaction -> {
String sql = "DELETE FROM Singers WHERE FirstName = 'Alice'";
long rowCount = transaction.executeUpdate(Statement.of(sql));
System.out.printf("%d record deleted.\n", rowCount);
return null;
});
}Node.js
// Imports the Google Cloud client library
const {Spanner} = require('@google-cloud/spanner');
/**
* TODO(developer): Uncomment the following lines before running the sample.
*/
// const projectId = 'my-project-id';
// const instanceId = 'my-instance';
// const databaseId = 'my-database';
// Creates a client
const spanner = new Spanner({
projectId: projectId,
});
// Gets a reference to a Cloud Spanner instance and database
const instance = spanner.instance(instanceId);
const database = instance.database(databaseId);
database.runTransaction(async (err, transaction) => {
if (err) {
console.error(err);
return;
}
try {
const [rowCount] = await transaction.runUpdate({
sql: "DELETE FROM Singers WHERE FirstName = 'Alice'",
});
console.log(`Successfully deleted ${rowCount} record.`);
await transaction.commit();
} catch (err) {
console.error('ERROR:', err);
} finally {
// Close the database when finished.
database.close();
}
});PHP
use Google\Cloud\Spanner\SpannerClient;
use Google\Cloud\Spanner\Transaction;
/**
* Deletes sample data in the database with a DML statement.
*
* @param string $instanceId The Spanner instance ID.
* @param string $databaseId The Spanner database ID.
*/
function delete_data_with_dml(string $instanceId, string $databaseId): void
{
$spanner = new SpannerClient();
$instance = $spanner->instance($instanceId);
$database = $instance->database($databaseId);
$database->runTransaction(function (Transaction $t) {
$rowCount = $t->executeUpdate(
"DELETE FROM Singers WHERE FirstName = 'Alice'");
$t->commit();
printf('Deleted %d row(s).' . PHP_EOL, $rowCount);
});
}Python
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
def delete_singers(transaction):
row_ct = transaction.execute_update(
"DELETE FROM Singers WHERE FirstName = 'Alice'"
)
print("{} record(s) deleted.".format(row_ct))
database.run_in_transaction(delete_singers)Ruby
# project_id = "Your Google Cloud project ID"
# instance_id = "Your Spanner instance ID"
# database_id = "Your Spanner database ID"
require "google/cloud/spanner"
spanner = Google::Cloud::Spanner.new project: project_id
client = spanner.client instance_id, database_id
row_count = 0
client.transaction do |transaction|
row_count = transaction.execute_update(
"DELETE FROM Singers WHERE FirstName = 'Alice'"
)
end
puts "#{row_count} record deleted."以下示例（仅适用于 GoogleSQL 方言数据库）使用包含绑定参数的 STRUCT 来更新按 FirstName 和 LastName 过滤的行中的 LastName。
GoogleSQL
C++
void DmlStructs(google::cloud::spanner::Client client) {
namespace spanner = ::google::cloud::spanner;
std::int64_t rows_modified = 0;
auto commit_result =
client.Commit([&client, &rows_modified](spanner::Transaction const& txn)
-> google::cloud::StatusOr<spanner::Mutations> {
auto singer_info = std::make_tuple("Marc", "Richards");
auto sql = spanner::SqlStatement(
"UPDATE Singers SET FirstName = 'Keith' WHERE "
"STRUCT<FirstName String, LastName String>(FirstName, LastName) "
"= @name",
{{"name", spanner::Value(std::move(singer_info))}});
auto dml_result = client.ExecuteDml(txn, std::move(sql));
if (!dml_result) return std::move(dml_result).status();
rows_modified = dml_result->RowsModified();
return spanner::Mutations{};
});
if (!commit_result) throw std::move(commit_result).status();
std::cout << rows_modified
<< " update was successful [spanner_dml_structs]\n";
}C#
using Google.Cloud.Spanner.Data;
using System;
using System.Threading.Tasks;
public class UpdateUsingDmlWithStructCoreAsyncSample
{
public async Task<int> UpdateUsingDmlWithStructCoreAsync(string projectId, string instanceId, string databaseId)
{
var nameStruct = new SpannerStruct
{
{ "FirstName", SpannerDbType.String, "Timothy" },
{ "LastName", SpannerDbType.String, "Campbell" }
};
string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";
using var connection = new SpannerConnection(connectionString);
await connection.OpenAsync();
using var cmd = connection.CreateDmlCommand("UPDATE Singers SET LastName = 'Grant' WHERE STRUCT<FirstName STRING, LastName STRING>(FirstName, LastName) = @name");
cmd.Parameters.Add("name", nameStruct.GetSpannerDbType(), nameStruct);
int rowCount = await cmd.ExecuteNonQueryAsync();
Console.WriteLine($"{rowCount} row(s) updated...");
return rowCount;
}
}Go
import (
"context"
"fmt"
"io"
"cloud.google.com/go/spanner"
)
func updateUsingDMLStruct(w io.Writer, db string) error {
ctx := context.Background()
client, err := spanner.NewClient(ctx, db)
if err != nil {
return err
}
defer client.Close()
_, err = client.ReadWriteTransaction(ctx, func(ctx context.Context, txn *spanner.ReadWriteTransaction) error {
type name struct {
FirstName string
LastName string
}
var singerInfo = name{"Timothy", "Campbell"}
stmt := spanner.Statement{
SQL: `Update Singers Set LastName = 'Grant'
WHERE STRUCT<FirstName String, LastName String>(Firstname, LastName) = @name`,
Params: map[string]interface{}{"name": singerInfo},
}
rowCount, err := txn.Update(ctx, stmt)
if err != nil {
return err
}
fmt.Fprintf(w, "%d record(s) inserted.\n", rowCount)
return nil
})
return err
}
Java
static void updateUsingDmlWithStruct(DatabaseClient dbClient) {
Struct name =
Struct.newBuilder().set("FirstName").to("Timothy").set("LastName").to("Campbell").build();
Statement s =
Statement.newBuilder(
"UPDATE Singers SET LastName = 'Grant' "
+ "WHERE STRUCT<FirstName STRING, LastName STRING>(FirstName, LastName) "
+ "= @name")
.bind("name")
.to(name)
.build();
dbClient
.readWriteTransaction()
.run(transaction -> {
long rowCount = transaction.executeUpdate(s);
System.out.printf("%d record updated.\n", rowCount);
return null;
});
}Node.js
// Imports the Google Cloud client library
const {Spanner} = require('@google-cloud/spanner');
const nameStruct = Spanner.struct({
FirstName: 'Timothy',
LastName: 'Campbell',
});
/**
* TODO(developer): Uncomment the following lines before running the sample.
*/
// const projectId = 'my-project-id';
// const instanceId = 'my-instance';
// const databaseId = 'my-database';
// Creates a client
const spanner = new Spanner({
projectId: projectId,
});
// Gets a reference to a Cloud Spanner instance and database
const instance = spanner.instance(instanceId);
const database = instance.database(databaseId);
database.runTransaction(async (err, transaction) => {
if (err) {
console.error(err);
return;
}
try {
const [rowCount] = await transaction.runUpdate({
sql: `UPDATE Singers SET LastName = 'Grant'
WHERE STRUCT<FirstName STRING, LastName STRING>(FirstName, LastName) = @name`,
params: {
name: nameStruct,
},
});
console.log(`Successfully updated ${rowCount} record.`);
await transaction.commit();
} catch (err) {
console.error('ERROR:', err);
} finally {
// Close the database when finished.
database.close();
}
});PHP
use Google\Cloud\Spanner\SpannerClient;
use Google\Cloud\Spanner\Database;
use Google\Cloud\Spanner\Transaction;
use Google\Cloud\Spanner\StructType;
use Google\Cloud\Spanner\StructValue;
/**
* Update data with a DML statement using Structs.
*
* The database and table must already exist and can be created using
* `create_database`.
* Example:
* ```
* insert_data($instanceId, $databaseId);
* ```
*
* @param string $instanceId The Spanner instance ID.
* @param string $databaseId The Spanner database ID.
*/
function update_data_with_dml_structs(string $instanceId, string $databaseId): void
{
$spanner = new SpannerClient();
$instance = $spanner->instance($instanceId);
$database = $instance->database($databaseId);
$database->runTransaction(function (Transaction $t) {
$nameValue = (new StructValue)
->add('FirstName', 'Timothy')
->add('LastName', 'Campbell');
$nameType = (new StructType)
->add('FirstName', Database::TYPE_STRING)
->add('LastName', Database::TYPE_STRING);
$rowCount = $t->executeUpdate(
"UPDATE Singers SET LastName = 'Grant' "
. 'WHERE STRUCT<FirstName STRING, LastName STRING>(FirstName, LastName) '
. '= @name',
[
'parameters' => [
'name' => $nameValue
],
'types' => [
'name' => $nameType
]
]);
$t->commit();
printf('Updated %d row(s).' . PHP_EOL, $rowCount);
});
}Python
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
record_type = param_types.Struct(
[
param_types.StructField("FirstName", param_types.STRING),
param_types.StructField("LastName", param_types.STRING),
]
)
record_value = ("Timothy", "Campbell")
def write_with_struct(transaction):
row_ct = transaction.execute_update(
"UPDATE Singers SET LastName = 'Grant' "
"WHERE STRUCT<FirstName STRING, LastName STRING>"
"(FirstName, LastName) = @name",
params={"name": record_value},
param_types={"name": record_type},
)
print("{} record(s) updated.".format(row_ct))
database.run_in_transaction(write_with_struct)Ruby
# project_id = "Your Google Cloud project ID"
# instance_id = "Your Spanner instance ID"
# database_id = "Your Spanner database ID"
require "google/cloud/spanner"
spanner = Google::Cloud::Spanner.new project: project_id
client = spanner.client instance_id, database_id
row_count = 0
name_struct = { FirstName: "Timothy", LastName: "Campbell" }
client.transaction do |transaction|
row_count = transaction.execute_update(
"UPDATE Singers SET LastName = 'Grant'
WHERE STRUCT<FirstName STRING, LastName STRING>(FirstName, LastName) = @name",
params: { name: name_struct }
)
end
puts "#{row_count} record updated."使用返回的 DML 语句修改数据
THEN RETURN 子句（GoogleSQL 方言数据库）或 RETURNING 子句（PostgreSQL 方言数据库）适用于您希望从修改后的行中提取数据的场景。如果要查看 DML 语句、默认值或生成的列中未指定的值，这种方法特别有用。
如需使用客户端库执行返回 DML 语句，请执行以下操作：
- 创建一个读写事务。
- 调用客户端库方法来执行查询，并传入返回的 DML 语句以获取结果。
以下代码示例在 Singers 表中插入一个新行，并返回所插入记录的生成列 FullName。
GoogleSQL
C++
void InsertUsingDmlReturning(google::cloud::spanner::Client client) {
// Insert records into SINGERS table and return the generated column
// FullName of the inserted records using `THEN RETURN FullName`.
auto commit = client.Commit(
[&client](google::cloud::spanner::Transaction txn)
-> google::cloud::StatusOr<google::cloud::spanner::Mutations> {
auto sql = google::cloud::spanner::SqlStatement(R"""(
INSERT INTO Singers (SingerId, FirstName, LastName)
VALUES (12, 'Melissa', 'Garcia'),
(13, 'Russell', 'Morales'),
(14, 'Jacqueline', 'Long'),
(15, 'Dylan', 'Shaw')
THEN RETURN FullName
)""");
using RowType = std::tuple<std::string>;
auto rows = client.ExecuteQuery(std::move(txn), std::move(sql));
// Note: This mutator might be re-run, or its effects discarded, so
// changing non-transactional state (e.g., by producing output) is,
// in general, not something to be imitated.
for (auto& row : google::cloud::spanner::StreamOf<RowType>(rows)) {
if (!row) return std::move(row).status();
std::cout << "FullName: " << std::get<0>(*row) << "\n";
}
std::cout << "Inserted row(s) count: " << rows.RowsModified() << "\n";
return google::cloud::spanner::Mutations{};
});
if (!commit) throw std::move(commit).status();
}C#
using Google.Cloud.Spanner.Data;
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
public class InsertUsingDmlReturningAsyncSample
{
public async Task<List<string>> InsertUsingDmlReturningAsync(string projectId, string instanceId, string databaseId)
{
string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";
using var connection = new SpannerConnection(connectionString);
await connection.OpenAsync();
// Insert records into the SINGERS table and return the
// generated column FullName of the inserted records using
// 'THEN RETURN FullName'.
// It is also possible to return all columns of all the
// inserted records by using 'THEN RETURN *'.
using var cmd = connection.CreateDmlCommand(
@"INSERT INTO Singers(SingerId, FirstName, LastName) VALUES
(6, 'Melissa', 'Garcia'),
(7, 'Russell', 'Morales'),
(8, 'Jacqueline', 'Long'),
(9, 'Dylan', 'Shaw') THEN RETURN FullName");
var reader = await cmd.ExecuteReaderAsync();
var insertedSingerNames = new List<string>();
while (await reader.ReadAsync())
{
insertedSingerNames.Add(reader.GetFieldValue<string>("FullName"));
}
Console.WriteLine($"{insertedSingerNames.Count} row(s) inserted...");
return insertedSingerNames;
}
}Go
import (
"context"
"fmt"
"io"
"cloud.google.com/go/spanner"
"google.golang.org/api/iterator"
)
func insertUsingDMLReturning(w io.Writer, db string) error {
ctx := context.Background()
client, err := spanner.NewClient(ctx, db)
if err != nil {
return err
}
defer client.Close()
// Insert records into the SINGERS table and returns the
// generated column FullName of the inserted records using
// 'THEN RETURN FullName'.
// It is also possible to return all columns of all the
// inserted records by using 'THEN RETURN *'.
_, err = client.ReadWriteTransaction(ctx, func(ctx context.Context, txn *spanner.ReadWriteTransaction) error {
stmt := spanner.Statement{
SQL: `INSERT INTO Singers (SingerId, FirstName, LastName)
VALUES (21, 'Melissa', 'Garcia'),
(22, 'Russell', 'Morales'),
(23, 'Jacqueline', 'Long'),
(24, 'Dylan', 'Shaw')
THEN RETURN FullName`,
}
iter := txn.Query(ctx, stmt)
defer iter.Stop()
for {
row, err := iter.Next()
if err == iterator.Done {
break
}
if err != nil {
return err
}
var fullName string
if err := row.Columns(&fullName); err != nil {
return err
}
fmt.Fprintf(w, "%s\n", fullName)
}
fmt.Fprintf(w, "%d record(s) inserted.\n", iter.RowCount)
return nil
})
return err
}
Java
import com.google.cloud.spanner.DatabaseClient;
import com.google.cloud.spanner.DatabaseId;
import com.google.cloud.spanner.ResultSet;
import com.google.cloud.spanner.Spanner;
import com.google.cloud.spanner.SpannerOptions;
import com.google.cloud.spanner.Statement;
public class InsertUsingDmlReturningSample {
static void insertUsingDmlReturning() {
// TODO(developer): Replace these variables before running the sample.
final String projectId = "my-project";
final String instanceId = "my-instance";
final String databaseId = "my-database";
insertUsingDmlReturning(projectId, instanceId, databaseId);
}
static void insertUsingDmlReturning(String projectId, String instanceId, String databaseId) {
try (Spanner spanner =
SpannerOptions.newBuilder()
.setProjectId(projectId)
.build()
.getService()) {
final DatabaseClient dbClient =
spanner.getDatabaseClient(DatabaseId.of(projectId, instanceId, databaseId));
// Insert records into the SINGERS table and returns the
// generated column FullName of the inserted records using
// ‘THEN RETURN FullName’.
// It is also possible to return all columns of all the
// inserted records by using ‘THEN RETURN *’.
dbClient
.readWriteTransaction()
.run(
transaction -> {
String sql =
"INSERT INTO Singers (SingerId, FirstName, LastName) VALUES "
+ "(12, 'Melissa', 'Garcia'), "
+ "(13, 'Russell', 'Morales'), "
+ "(14, 'Jacqueline', 'Long'), "
+ "(15, 'Dylan', 'Shaw') THEN RETURN FullName";
// readWriteTransaction.executeQuery(..) API should be used for executing
// DML statements with RETURNING clause.
try (ResultSet resultSet = transaction.executeQuery(Statement.of(sql))) {
while (resultSet.next()) {
System.out.println(resultSet.getString(0));
}
System.out.printf(
"Inserted row(s) count: %d\n", resultSet.getStats().getRowCountExact());
}
return null;
});
}
}
}Node.js
// Imports the Google Cloud client library.
const {Spanner} = require('@google-cloud/spanner');
/**
* TODO(developer): Uncomment the following lines before running the sample.
*/
// const projectId = 'my-project-id';
// const instanceId = 'my-instance';
// const databaseId = 'my-database';
// Creates a client
const spanner = new Spanner({
projectId: projectId,
});
function insertUsingDmlReturning(instanceId, databaseId) {
// Gets a reference to a Cloud Spanner instance and database.
const instance = spanner.instance(instanceId);
const database = instance.database(databaseId);
database.runTransaction(async (err, transaction) => {
if (err) {
console.error(err);
return;
}
try {
const [rows, stats] = await transaction.run({
sql: 'INSERT Singers (SingerId, FirstName, LastName) VALUES (@id, @firstName, @lastName) THEN RETURN FullName',
params: {
id: 18,
firstName: 'Virginia',
lastName: 'Watson',
},
});
const rowCount = Math.floor(stats[stats.rowCount]);
console.log(
`Successfully inserted ${rowCount} record into the Singers table.`
);
rows.forEach(row => {
console.log(row.toJSON().FullName);
});
await transaction.commit();
} catch (err) {
console.error('ERROR:', err);
} finally {
// Close the database when finished.
database.close();
}
});
}
insertUsingDmlReturning(instanceId, databaseId);PHP
use Google\Cloud\Spanner\SpannerClient;
/**
* Inserts sample data into the given database using DML returning.
*
* @param string $instanceId The Spanner instance ID.
* @param string $databaseId The Spanner database ID.
*/
function insert_dml_returning(string $instanceId, string $databaseId): void
{
$spanner = new SpannerClient();
$instance = $spanner->instance($instanceId);
$database = $instance->database($databaseId);
// Insert records into SINGERS table and returns the generated column
// FullName of the inserted records using ‘THEN RETURN FullName’. It is also
// possible to return all columns of all the inserted records by using
// ‘THEN RETURN *’.
$sql = 'INSERT INTO Singers (SingerId, FirstName, LastName) '
. "VALUES (12, 'Melissa', 'Garcia'), "
. "(13, 'Russell', 'Morales'), "
. "(14, 'Jacqueline', 'Long'), "
. "(15, 'Dylan', 'Shaw') "
. 'THEN RETURN FullName';
$transaction = $database->transaction();
$result = $transaction->execute($sql);
foreach ($result->rows() as $row) {
printf(
'%s inserted.' . PHP_EOL,
$row['FullName'],
);
}
printf(
'Inserted row(s) count: %d' . PHP_EOL,
$result->stats()['rowCountExact']
);
$transaction->commit();
}Python
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
# Insert records into the SINGERS table and returns the
# generated column FullName of the inserted records using
# 'THEN RETURN FullName'.
# It is also possible to return all columns of all the
# inserted records by using 'THEN RETURN *'.
def insert_singers(transaction):
results = transaction.execute_sql(
"INSERT INTO Singers (SingerId, FirstName, LastName) VALUES "
"(21, 'Luann', 'Chizoba'), "
"(22, 'Denis', 'Patricio'), "
"(23, 'Felxi', 'Ronan'), "
"(24, 'Dominik', 'Martyna') "
"THEN RETURN FullName"
)
for result in results:
print("FullName: {}".format(*result))
print("{} record(s) inserted.".format(results.stats.row_count_exact))
database.run_in_transaction(insert_singers)Ruby
require "google/cloud/spanner"
##
# This is a snippet for showcasing how to use DML return feature with insert
# operation.
#
# @param project_id [String] The ID of the Google Cloud project.
# @param instance_id [String] The ID of the spanner instance.
# @param database_id [String] The ID of the database.
#
def spanner_insert_dml_returning project_id:, instance_id:, database_id:
spanner = Google::Cloud::Spanner.new project: project_id
client = spanner.client instance_id, database_id
client.transaction do |transaction|
# Insert records into the SINGERS table and returns the generated column
# FullName of the inserted records using ‘THEN RETURN FullName’.
# It is also possible to return all columns of all the inserted records
# by using ‘THEN RETURN *’.
results = transaction.execute_query "INSERT INTO Singers (SingerId, FirstName, LastName)
VALUES (12, 'Melissa', 'Garcia'), (13, 'Russell', 'Morales'), (14, 'Jacqueline', 'Long'), (15, 'Dylan', 'Shaw')
THEN RETURN FullName"
results.rows.each do |row|
puts "Inserted singers with FullName: #{row[:FullName]}"
end
puts "Inserted row(s) count: #{results.row_count}"
end
end
PostgreSQL
C++
void InsertUsingDmlReturning(google::cloud::spanner::Client client) {
// Insert records into SINGERS table and return the generated column
// FullName of the inserted records using `RETURNING FullName`.
auto commit = client.Commit(
[&client](google::cloud::spanner::Transaction txn)
-> google::cloud::StatusOr<google::cloud::spanner::Mutations> {
auto sql = google::cloud::spanner::SqlStatement(R"""(
INSERT INTO Singers (SingerId, FirstName, LastName)
VALUES (12, 'Melissa', 'Garcia'),
(13, 'Russell', 'Morales'),
(14, 'Jacqueline', 'Long'),
(15, 'Dylan', 'Shaw')
RETURNING FullName
)""");
using RowType = std::tuple<std::string>;
auto rows = client.ExecuteQuery(std::move(txn), std::move(sql));
for (auto& row : google::cloud::spanner::StreamOf<RowType>(rows)) {
if (!row) return std::move(row).status();
std::cout << "FullName: " << std::get<0>(*row) << "\n";
}
std::cout << "Inserted row(s) count: " << rows.RowsModified() << "\n";
return google::cloud::spanner::Mutations{};
});
if (!commit) throw std::move(commit).status();
}C#
using Google.Cloud.Spanner.Data;
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
public class InsertUsingDmlReturningAsyncPostgresSample
{
public async Task<List<string>> InsertUsingDmlReturningAsyncPostgres(string projectId, string instanceId, string databaseId)
{
string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";
using var connection = new SpannerConnection(connectionString);
await connection.OpenAsync();
// Insert records into SINGERS table and return the
// generated column FullName of the inserted records
// using 'RETURNING FullName'.
// It is also possible to return all columns of all the
// inserted records by using 'RETURNING *'.
using var cmd = connection.CreateDmlCommand(
@"INSERT INTO Singers(SingerId, FirstName, LastName) VALUES
(6, 'Melissa', 'Garcia'),
(7, 'Russell', 'Morales'),
(8, 'Jacqueline', 'Long'),
(9, 'Dylan', 'Shaw') RETURNING FullName");
var reader = await cmd.ExecuteReaderAsync();
var insertedSingerNames = new List<string>();
while (await reader.ReadAsync())
{
insertedSingerNames.Add(reader.GetFieldValue<string>("fullname"));
}
Console.WriteLine($"{insertedSingerNames.Count} row(s) inserted...");
return insertedSingerNames;
}
}Go
import (
"context"
"fmt"
"io"
"cloud.google.com/go/spanner"
"google.golang.org/api/iterator"
)
func pgInsertUsingDMLReturning(w io.Writer, db string) error {
ctx := context.Background()
client, err := spanner.NewClient(ctx, db)
if err != nil {
return err
}
defer client.Close()
// Insert records into the SINGERS table and returns the
// generated column FullName of the inserted records using
// 'RETURNING FullName'.
// It is also possible to return all columns of all the
// inserted records by using 'RETURNING *'.
_, err = client.ReadWriteTransaction(ctx, func(ctx context.Context, txn *spanner.ReadWriteTransaction) error {
stmt := spanner.Statement{
SQL: `INSERT INTO Singers (SingerId, FirstName, LastName)
VALUES (21, 'Melissa', 'Garcia'),
(22, 'Russell', 'Morales'),
(23, 'Jacqueline', 'Long'),
(24, 'Dylan', 'Shaw')
RETURNING FullName`,
}
iter := txn.Query(ctx, stmt)
defer iter.Stop()
for {
row, err := iter.Next()
if err == iterator.Done {
break
}
if err != nil {
return err
}
var fullName string
if err := row.Columns(&fullName); err != nil {
return err
}
fmt.Fprintf(w, "%s\n", fullName)
}
fmt.Fprintf(w, "%d record(s) inserted.\n", iter.RowCount)
return nil
})
return err
}
Java
import com.google.cloud.spanner.DatabaseClient;
import com.google.cloud.spanner.DatabaseId;
import com.google.cloud.spanner.ResultSet;
import com.google.cloud.spanner.Spanner;
import com.google.cloud.spanner.SpannerOptions;
import com.google.cloud.spanner.Statement;
public class PgInsertUsingDmlReturningSample {
static void insertUsingDmlReturning() {
// TODO(developer): Replace these variables before running the sample.
final String projectId = "my-project";
final String instanceId = "my-instance";
final String databaseId = "my-database";
insertUsingDmlReturning(projectId, instanceId, databaseId);
}
static void insertUsingDmlReturning(String projectId, String instanceId, String databaseId) {
try (Spanner spanner =
SpannerOptions.newBuilder()
.setProjectId(projectId)
.build()
.getService()) {
final DatabaseClient dbClient =
spanner.getDatabaseClient(DatabaseId.of(projectId, instanceId, databaseId));
// Insert records into SINGERS table and returns the
// generated column FullName of the inserted records
// using ‘RETURNING FullName’.
// It is also possible to return all columns of all the
// inserted records by using ‘RETURNING *’.
dbClient
.readWriteTransaction()
.run(
transaction -> {
String sql =
"INSERT INTO Singers (SingerId, FirstName, LastName) VALUES "
+ "(12, 'Melissa', 'Garcia'), "
+ "(13, 'Russell', 'Morales'), "
+ "(14, 'Jacqueline', 'Long'), "
+ "(15, 'Dylan', 'Shaw') RETURNING FullName";
// readWriteTransaction.executeQuery(..) API should be used for executing
// DML statements with RETURNING clause.
try (ResultSet resultSet = transaction.executeQuery(Statement.of(sql))) {
while (resultSet.next()) {
System.out.println(resultSet.getString(0));
}
System.out.printf(
"Inserted row(s) count: %d\n", resultSet.getStats().getRowCountExact());
}
return null;
});
}
}
}Node.js
// Imports the Google Cloud client library.
const {Spanner} = require('@google-cloud/spanner');
/**
* TODO(developer): Uncomment the following lines before running the sample.
*/
// const projectId = 'my-project-id';
// const instanceId = 'my-instance';
// const databaseId = 'my-database';
// Creates a client
const spanner = new Spanner({
projectId: projectId,
});
function pgInsertUsingDmlReturning(instanceId, databaseId) {
// Gets a reference to a Cloud Spanner instance and database.
const instance = spanner.instance(instanceId);
const database = instance.database(databaseId);
database.runTransaction(async (err, transaction) => {
if (err) {
console.error(err);
return;
}
try {
const [rows, stats] = await transaction.run({
sql: 'INSERT Into Singers (SingerId, FirstName, LastName) VALUES ($1, $2, $3) RETURNING FullName',
params: {
p1: 18,
p2: 'Virginia',
p3: 'Watson',
},
});
const rowCount = Math.floor(stats[stats.rowCount]);
console.log(
`Successfully inserted ${rowCount} record into the Singers table.`
);
rows.forEach(row => {
console.log(row.toJSON().fullname);
});
await transaction.commit();
} catch (err) {
console.error('ERROR:', err);
} finally {
// Close the database when finished.
database.close();
}
});
}
pgInsertUsingDmlReturning(instanceId, databaseId);PHP
use Google\Cloud\Spanner\SpannerClient;
/**
* Inserts sample data into the given postgresql database using DML returning.
*
* @param string $instanceId The Spanner instance ID.
* @param string $databaseId The Spanner database ID.
*/
function pg_insert_dml_returning(string $instanceId, string $databaseId): void
{
$spanner = new SpannerClient();
$instance = $spanner->instance($instanceId);
$database = $instance->database($databaseId);
// Insert records into SINGERS table and returns the generated column
// FullName of the inserted records using ‘RETURNING FullName’. It is also
// possible to return all columns of all the inserted records by using
// ‘RETURNING *’.
$sql = 'INSERT INTO Singers (Singerid, FirstName, LastName) '
. "VALUES (12, 'Melissa', 'Garcia'), "
. "(13, 'Russell', 'Morales'), "
. "(14, 'Jacqueline', 'Long'), "
. "(15, 'Dylan', 'Shaw') "
. 'RETURNING FullName';
$transaction = $database->transaction();
$result = $transaction->execute($sql);
foreach ($result->rows() as $row) {
printf(
'%s inserted.' . PHP_EOL,
$row['fullname'],
);
}
printf(
'Inserted row(s) count: %d' . PHP_EOL,
$result->stats()['rowCountExact']
);
$transaction->commit();
}Python
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
# Insert records into the SINGERS table and returns the
# generated column FullName of the inserted records using
# 'RETURNING FullName'.
# It is also possible to return all columns of all the
# inserted records by using 'RETURNING *'.
def insert_singers(transaction):
results = transaction.execute_sql(
"INSERT INTO Singers (SingerId, FirstName, LastName) VALUES "
"(21, 'Luann', 'Chizoba'), "
"(22, 'Denis', 'Patricio'), "
"(23, 'Felxi', 'Ronan'), "
"(24, 'Dominik', 'Martyna') "
"RETURNING FullName"
)
for result in results:
print("FullName: {}".format(*result))
print("{} record(s) inserted.".format(results.stats.row_count_exact))
database.run_in_transaction(insert_singers)Ruby
require "google/cloud/spanner"
##
# This is a snippet for showcasing how to use DML return feature with insert
# operation in PostgreSql.
#
# @param project_id [String] The ID of the Google Cloud project.
# @param instance_id [String] The ID of the spanner instance.
# @param database_id [String] The ID of the database.
#
def spanner_postgresql_insert_dml_returning project_id:, instance_id:, database_id:
spanner = Google::Cloud::Spanner.new project: project_id
client = spanner.client instance_id, database_id
client.transaction do |transaction|
# Insert records into SINGERS table and returns the generated column
# FullName of the inserted records using ‘RETURNING FullName’.
# It is also possible to return all columns of all the inserted
# records by using ‘RETURNING *’.
results = transaction.execute_query "INSERT INTO Singers (SingerId, FirstName, LastName)
VALUES (12, 'Melissa', 'Garcia'), (13, 'Russell', 'Morales'), (14, 'Jacqueline', 'Long'), (15, 'Dylan', 'Shaw')
RETURNING FullName"
results.rows.each do |row|
puts "Inserted singers with FullName: #{row[:fullname]}"
end
puts "Inserted row(s) count: #{results.row_count}"
end
end
以下代码示例根据 WHERE 子句更新 Albums 表的 MarketingBudget 列，并返回已更新记录的经过修改的 MarketingBudget 列。
GoogleSQL
C++
void UpdateUsingDmlReturning(google::cloud::spanner::Client client) {
// Update MarketingBudget column for records satisfying a particular
// condition and return the modified MarketingBudget column of the
// updated records using `THEN RETURN MarketingBudget`.
auto commit = client.Commit(
[&client](google::cloud::spanner::Transaction txn)
-> google::cloud::StatusOr<google::cloud::spanner::Mutations> {
auto sql = google::cloud::spanner::SqlStatement(R"""(
UPDATE Albums SET MarketingBudget = MarketingBudget * 2
WHERE SingerId = 1 AND AlbumId = 1
THEN RETURN MarketingBudget
)""");
using RowType = std::tuple<absl::optional<std::int64_t>>;
auto rows = client.ExecuteQuery(std::move(txn), std::move(sql));
// Note: This mutator might be re-run, or its effects discarded, so
// changing non-transactional state (e.g., by producing output) is,
// in general, not something to be imitated.
for (auto& row : google::cloud::spanner::StreamOf<RowType>(rows)) {
if (!row) return std::move(row).status();
std::cout << "MarketingBudget: ";
if (std::get<0>(*row).has_value()) {
std::cout << *std::get<0>(*row);
} else {
std::cout << "NULL";
}
std::cout << "\n";
}
std::cout << "Updated row(s) count: " << rows.RowsModified() << "\n";
return google::cloud::spanner::Mutations{};
});
if (!commit) throw std::move(commit).status();
}C#
using Google.Cloud.Spanner.Data;
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
public class UpdateUsingDmlReturningAsyncSample
{
public async Task<List<long>> UpdateUsingDmlReturningAsync(string projectId, string instanceId, string databaseId)
{
string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";
using var connection = new SpannerConnection(connectionString);
await connection.OpenAsync();
// Update MarketingBudget column for records satisfying
// a particular condition and return the modified
// MarketingBudget column of the updated records using
// 'THEN RETURN MarketingBudget'.
// It is also possible to return all columns of all the
// updated records by using 'THEN RETURN *'.
using var cmd = connection.CreateDmlCommand("UPDATE Albums SET MarketingBudget = MarketingBudget * 2 WHERE SingerId = 1 and AlbumId = 1 THEN RETURN MarketingBudget");
var reader = await cmd.ExecuteReaderAsync();
var updatedMarketingBudgets = new List<long>();
while (await reader.ReadAsync())
{
updatedMarketingBudgets.Add(reader.GetFieldValue<long>("MarketingBudget"));
}
Console.WriteLine($"{updatedMarketingBudgets.Count} row(s) updated...");
return updatedMarketingBudgets;
}
}Go
import (
"context"
"fmt"
"io"
"cloud.google.com/go/spanner"
"google.golang.org/api/iterator"
)
func updateUsingDMLReturning(w io.Writer, db string) error {
ctx := context.Background()
client, err := spanner.NewClient(ctx, db)
if err != nil {
return err
}
defer client.Close()
// Update MarketingBudget column for records satisfying
// a particular condition and returns the modified
// MarketingBudget column of the updated records using
// 'THEN RETURN MarketingBudget'.
// It is also possible to return all columns of all the
// updated records by using 'THEN RETURN *'.
_, err = client.ReadWriteTransaction(ctx, func(ctx context.Context, txn *spanner.ReadWriteTransaction) error {
stmt := spanner.Statement{
SQL: `UPDATE Albums
SET MarketingBudget = MarketingBudget * 2
WHERE SingerId = 1 and AlbumId = 1
THEN RETURN MarketingBudget`,
}
iter := txn.Query(ctx, stmt)
defer iter.Stop()
for {
row, err := iter.Next()
if err == iterator.Done {
break
}
if err != nil {
return err
}
var marketingBudget int64
if err := row.Columns(&marketingBudget); err != nil {
return err
}
fmt.Fprintf(w, "%d\n", marketingBudget)
}
fmt.Fprintf(w, "%d record(s) updated.\n", iter.RowCount)
return nil
})
return err
}
Java
import com.google.cloud.spanner.DatabaseClient;
import com.google.cloud.spanner.DatabaseId;
import com.google.cloud.spanner.ResultSet;
import com.google.cloud.spanner.Spanner;
import com.google.cloud.spanner.SpannerOptions;
import com.google.cloud.spanner.Statement;
public class UpdateUsingDmlReturningSample {
static void updateUsingDmlReturning() {
// TODO(developer): Replace these variables before running the sample.
final String projectId = "my-project";
final String instanceId = "my-instance";
final String databaseId = "my-database";
updateUsingDmlReturning(projectId, instanceId, databaseId);
}
static void updateUsingDmlReturning(String projectId, String instanceId, String databaseId) {
try (Spanner spanner =
SpannerOptions.newBuilder()
.setProjectId(projectId)
.build()
.getService()) {
final DatabaseClient dbClient =
spanner.getDatabaseClient(DatabaseId.of(projectId, instanceId, databaseId));
// Update MarketingBudget column for records satisfying
// a particular condition and returns the modified
// MarketingBudget column of the updated records using
// ‘THEN RETURN MarketingBudget’.
// It is also possible to return all columns of all the
// updated records by using ‘THEN RETURN *’.
dbClient
.readWriteTransaction()
.run(
transaction -> {
String sql =
"UPDATE Albums "
+ "SET MarketingBudget = MarketingBudget * 2 "
+ "WHERE SingerId = 1 and AlbumId = 1 "
+ "THEN RETURN MarketingBudget";
// readWriteTransaction.executeQuery(..) API should be used for executing
// DML statements with RETURNING clause.
try (ResultSet resultSet = transaction.executeQuery(Statement.of(sql))) {
while (resultSet.next()) {
System.out.printf("%d\n", resultSet.getLong(0));
}
System.out.printf(
"Updated row(s) count: %d\n", resultSet.getStats().getRowCountExact());
}
return null;
});
}
}
}Node.js
// Imports the Google Cloud client library.
const {Spanner} = require('@google-cloud/spanner');
/**
* TODO(developer): Uncomment the following lines before running the sample.
*/
// const projectId = 'my-project-id';
// const instanceId = 'my-instance';
// const databaseId = 'my-database';
// Creates a client
const spanner = new Spanner({
projectId: projectId,
});
function updateUsingDmlReturning(instanceId, databaseId) {
// Gets a reference to a Cloud Spanner instance and database.
const instance = spanner.instance(instanceId);
const database = instance.database(databaseId);
database.runTransaction(async (err, transaction) => {
if (err) {
console.error(err);
return;
}
try {
const [rows, stats] = await transaction.run({
sql: 'UPDATE Albums SET MarketingBudget = 2000000 WHERE SingerId = 1 and AlbumId = 1 THEN RETURN MarketingBudget',
});
const rowCount = Math.floor(stats[stats.rowCount]);
console.log(
`Successfully updated ${rowCount} record into the Albums table.`
);
rows.forEach(row => {
console.log(row.toJSON().MarketingBudget);
});
await transaction.commit();
} catch (err) {
console.error('ERROR:', err);
} finally {
// Close the database when finished.
database.close();
}
});
}
updateUsingDmlReturning(instanceId, databaseId);PHP
use Google\Cloud\Spanner\SpannerClient;
/**
* Update the given database using DML returning.
*
* @param string $instanceId The Spanner instance ID.
* @param string $databaseId The Spanner database ID.
*/
function update_dml_returning(string $instanceId, string $databaseId): void
{
$spanner = new SpannerClient();
$instance = $spanner->instance($instanceId);
$database = $instance->database($databaseId);
$transaction = $database->transaction();
// Update MarketingBudget column for records satisfying a particular
// condition and returns the modified MarketingBudget column of the updated
// records using ‘THEN RETURN MarketingBudget’. It is also possible to return
// all columns of all the updated records by using ‘THEN RETURN *’.
$result = $transaction->execute(
'UPDATE Albums '
. 'SET MarketingBudget = MarketingBudget * 2 '
. 'WHERE SingerId = 1 and AlbumId = 1 '
. 'THEN RETURN MarketingBudget'
);
foreach ($result->rows() as $row) {
printf('MarketingBudget: %s' . PHP_EOL, $row['MarketingBudget']);
}
printf(
'Updated row(s) count: %d' . PHP_EOL,
$result->stats()['rowCountExact']
);
$transaction->commit();
}Python
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
# Update MarketingBudget column for records satisfying
# a particular condition and returns the modified
# MarketingBudget column of the updated records using
# 'THEN RETURN MarketingBudget'.
# It is also possible to return all columns of all the
# updated records by using 'THEN RETURN *'.
def update_albums(transaction):
results = transaction.execute_sql(
"UPDATE Albums "
"SET MarketingBudget = MarketingBudget * 2 "
"WHERE SingerId = 1 and AlbumId = 1 "
"THEN RETURN MarketingBudget"
)
for result in results:
print("MarketingBudget: {}".format(*result))
print("{} record(s) updated.".format(results.stats.row_count_exact))
database.run_in_transaction(update_albums)Ruby
require "google/cloud/spanner"
##
# This is a snippet for showcasing how to use DML return feature with update
# operation.
#
# @param project_id [String] The ID of the Google Cloud project.
# @param instance_id [String] The ID of the spanner instance.
# @param database_id [String] The ID of the database.
#
def spanner_update_dml_returning project_id:, instance_id:, database_id:
spanner = Google::Cloud::Spanner.new project: project_id
client = spanner.client instance_id, database_id
client.transaction do |transaction|
# Update MarketingBudget column for records satisfying a particular
# condition and returns the modified MarketingBudget column of the
# updated records using ‘THEN RETURN MarketingBudget’.
#
# It is also possible to return all columns of all the updated records
# by using ‘THEN RETURN *’.
results = transaction.execute_query "UPDATE Albums SET MarketingBudget = MarketingBudget * 2
WHERE SingerId = 1 and AlbumId = 1
THEN RETURN MarketingBudget"
results.rows.each do |row|
puts "Updated Album with MarketingBudget: #{row[:MarketingBudget]}"
end
puts "Updated row(s) count: #{results.row_count}"
end
end
PostgreSQL
C++
void UpdateUsingDmlReturning(google::cloud::spanner::Client client) {
// Update MarketingBudget column for records satisfying a particular
// condition and return the modified MarketingBudget column of the
// updated records using `RETURNING MarketingBudget`.
auto commit = client.Commit(
[&client](google::cloud::spanner::Transaction txn)
-> google::cloud::StatusOr<google::cloud::spanner::Mutations> {
auto sql = google::cloud::spanner::SqlStatement(R"""(
UPDATE Albums SET MarketingBudget = MarketingBudget * 2
WHERE SingerId = 1 AND AlbumId = 1
RETURNING MarketingBudget
)""");
using RowType = std::tuple<absl::optional<std::int64_t>>;
auto rows = client.ExecuteQuery(std::move(txn), std::move(sql));
for (auto& row : google::cloud::spanner::StreamOf<RowType>(rows)) {
if (!row) return std::move(row).status();
std::cout << "MarketingBudget: ";
if (std::get<0>(*row).has_value()) {
std::cout << *std::get<0>(*row);
} else {
std::cout << "NULL";
}
std::cout << "\n";
}
std::cout << "Updated row(s) count: " << rows.RowsModified() << "\n";
return google::cloud::spanner::Mutations{};
});
if (!commit) throw std::move(commit).status();
}C#
using Google.Cloud.Spanner.Data;
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
public class UpdateUsingDmlReturningAsyncPostgresSample
{
public async Task<List<long>> UpdateUsingDmlReturningAsyncPostgres(string projectId, string instanceId, string databaseId)
{
string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";
using var connection = new SpannerConnection(connectionString);
await connection.OpenAsync();
// Update MarketingBudget column for records satisfying
// a particular condition and return the modified
// MarketingBudget column of the updated records using
// 'RETURNING MarketingBudget'.
// It is also possible to return all columns of all the
// updated records by using 'RETURNING *'.
using var cmd = connection.CreateDmlCommand("UPDATE Albums SET MarketingBudget = MarketingBudget * 2 WHERE SingerId = 14 and AlbumId = 20 RETURNING MarketingBudget");
var reader = await cmd.ExecuteReaderAsync();
var updatedMarketingBudgets = new List<long>();
while (await reader.ReadAsync())
{
updatedMarketingBudgets.Add(reader.GetFieldValue<long>("marketingbudget"));
}
Console.WriteLine($"{updatedMarketingBudgets.Count} row(s) updated...");
return updatedMarketingBudgets;
}
}Go
import (
"context"
"fmt"
"io"
"cloud.google.com/go/spanner"
"google.golang.org/api/iterator"
)
func pgUpdateUsingDMLReturning(w io.Writer, db string) error {
ctx := context.Background()
client, err := spanner.NewClient(ctx, db)
if err != nil {
return err
}
defer client.Close()
// Update MarketingBudget column for records satisfying
// a particular condition and returns the modified
// MarketingBudget column of the updated records using
// 'RETURNING MarketingBudget'.
// It is also possible to return all columns of all the
// updated records by using 'RETURNING *'.
_, err = client.ReadWriteTransaction(ctx, func(ctx context.Context, txn *spanner.ReadWriteTransaction) error {
stmt := spanner.Statement{
SQL: `UPDATE Albums
SET MarketingBudget = MarketingBudget * 2
WHERE SingerId = 1 and AlbumId = 1
RETURNING MarketingBudget`,
}
iter := txn.Query(ctx, stmt)
defer iter.Stop()
for {
row, err := iter.Next()
if err == iterator.Done {
break
}
if err != nil {
return err
}
var marketingBudget int64
if err := row.Columns(&marketingBudget); err != nil {
return err
}
fmt.Fprintf(w, "%d\n", marketingBudget)
}
fmt.Fprintf(w, "%d record(s) updated.\n", iter.RowCount)
return nil
})
return err
}
Java
import com.google.cloud.spanner.DatabaseClient;
import com.google.cloud.spanner.DatabaseId;
import com.google.cloud.spanner.ResultSet;
import com.google.cloud.spanner.Spanner;
import com.google.cloud.spanner.SpannerOptions;
import com.google.cloud.spanner.Statement;
public class PgUpdateUsingDmlReturningSample {
static void updateUsingDmlReturning() {
// TODO(developer): Replace these variables before running the sample.
final String projectId = "my-project";
final String instanceId = "my-instance";
final String databaseId = "my-database";
updateUsingDmlReturning(projectId, instanceId, databaseId);
}
static void updateUsingDmlReturning(String projectId, String instanceId, String databaseId) {
try (Spanner spanner =
SpannerOptions.newBuilder()
.setProjectId(projectId)
.build()
.getService()) {
final DatabaseClient dbClient =
spanner.getDatabaseClient(DatabaseId.of(projectId, instanceId, databaseId));
// Update MarketingBudget column for records satisfying
// a particular condition and returns the modified
// MarketingBudget column of the updated records using
// ‘RETURNING MarketingBudget’.
// It is also possible to return all columns of all the
// updated records by using ‘RETURNING *’.
dbClient
.readWriteTransaction()
.run(
transaction -> {
String sql =
"UPDATE Albums "
+ "SET MarketingBudget = MarketingBudget * 2 "
+ "WHERE SingerId = 1 and AlbumId = 1 "
+ "RETURNING MarketingBudget";
// readWriteTransaction.executeQuery(..) API should be used for executing
// DML statements with RETURNING clause.
try (ResultSet resultSet = transaction.executeQuery(Statement.of(sql))) {
while (resultSet.next()) {
System.out.printf("%d\n", resultSet.getLong(0));
}
System.out.printf(
"Updated row(s) count: %d\n", resultSet.getStats().getRowCountExact());
}
return null;
});
}
}
}Node.js
// Imports the Google Cloud client library.
const {Spanner} = require('@google-cloud/spanner');
/**
* TODO(developer): Uncomment the following lines before running the sample.
*/
// const projectId = 'my-project-id';
// const instanceId = 'my-instance';
// const databaseId = 'my-database';
// Creates a client
const spanner = new Spanner({
projectId: projectId,
});
function pgUpdateUsingDmlReturning(instanceId, databaseId) {
// Gets a reference to a Cloud Spanner instance and database.
const instance = spanner.instance(instanceId);
const database = instance.database(databaseId);
database.runTransaction(async (err, transaction) => {
if (err) {
console.error(err);
return;
}
try {
const [rows, stats] = await transaction.run({
sql: 'UPDATE singers SET FirstName = $1, LastName = $2 WHERE singerid = $3 RETURNING FullName',
params: {
p1: 'Virginia1',
p2: 'Watson1',
p3: 18,
},
});
const rowCount = Math.floor(stats[stats.rowCount]);
console.log(
`Successfully updated ${rowCount} record into the Singers table.`
);
rows.forEach(row => {
console.log(row.toJSON().fullname);
});
await transaction.commit();
} catch (err) {
console.error('ERROR:', err);
} finally {
// Close the database when finished.
database.close();
}
});
}
pgUpdateUsingDmlReturning(instanceId, databaseId);PHP
use Google\Cloud\Spanner\SpannerClient;
/**
* Update the given postgresql database using DML returning.
*
* @param string $instanceId The Spanner instance ID.
* @param string $databaseId The Spanner database ID.
*/
function pg_update_dml_returning(string $instanceId, string $databaseId): void
{
$spanner = new SpannerClient();
$instance = $spanner->instance($instanceId);
$database = $instance->database($databaseId);
$transaction = $database->transaction();
// Update MarketingBudget column for records satisfying a particular
// condition and returns the modified MarketingBudget column of the updated
// records using ‘RETURNING MarketingBudget’. It is also possible to return
// all columns of all the updated records by using ‘RETURNING *’.
$result = $transaction->execute(
'UPDATE Albums '
. 'SET MarketingBudget = MarketingBudget * 2 '
. 'WHERE SingerId = 1 and AlbumId = 1'
. 'RETURNING MarketingBudget'
);
foreach ($result->rows() as $row) {
printf('MarketingBudget: %s' . PHP_EOL, $row['marketingbudget']);
}
printf(
'Updated row(s) count: %d' . PHP_EOL,
$result->stats()['rowCountExact']
);
$transaction->commit();
}Python
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
# Update MarketingBudget column for records satisfying
# a particular condition and returns the modified
# MarketingBudget column of the updated records using
# 'RETURNING MarketingBudget'.
# It is also possible to return all columns of all the
# updated records by using 'RETURNING *'.
def update_albums(transaction):
results = transaction.execute_sql(
"UPDATE Albums "
"SET MarketingBudget = MarketingBudget * 2 "
"WHERE SingerId = 1 and AlbumId = 1 "
"RETURNING MarketingBudget"
)
for result in results:
print("MarketingBudget: {}".format(*result))
print("{} record(s) updated.".format(results.stats.row_count_exact))
database.run_in_transaction(update_albums)Ruby
require "google/cloud/spanner"
##
# This is a snippet for showcasing how to use DML return feature with update
# operation in PostgreSql.
#
# @param project_id [String] The ID of the Google Cloud project.
# @param instance_id [String] The ID of the spanner instance.
# @param database_id [String] The ID of the database.
#
def spanner_postgresql_update_dml_returning project_id:, instance_id:, database_id:
spanner = Google::Cloud::Spanner.new project: project_id
client = spanner.client instance_id, database_id
client.transaction do |transaction|
# Update MarketingBudget column for records satisfying a particular
# condition and returns the modified MarketingBudget column of the
# updated records using ‘RETURNING MarketingBudget’.
# It is also possible to return all columns of all the updated records
# by using ‘RETURNING *’.
results = transaction.execute_query "UPDATE Albums SET MarketingBudget = MarketingBudget * 2
WHERE SingerId = 1 and AlbumId = 1
RETURNING MarketingBudget"
results.rows.each do |row|
puts "Updated Albums with MarketingBudget: #{row[:marketingbudget]}"
end
puts "Updated row(s) count: #{results.row_count}"
end
end
以下代码示例删除 Singers 表中 FirstName 列为 Alice 的所有行，并返回已删除记录的 SingerId 和 FullName 列。
GoogleSQL
C++
void DeleteUsingDmlReturning(google::cloud::spanner::Client client) {
// Delete records from SINGERS table satisfying a particular condition
// and return the SingerId and FullName column of the deleted records
// using `THEN RETURN SingerId, FullName'.
auto commit = client.Commit(
[&client](google::cloud::spanner::Transaction txn)
-> google::cloud::StatusOr<google::cloud::spanner::Mutations> {
auto sql = google::cloud::spanner::SqlStatement(R"""(
DELETE FROM Singers
WHERE FirstName = 'Alice'
THEN RETURN SingerId, FullName
)""");
using RowType = std::tuple<std::int64_t, std::string>;
auto rows = client.ExecuteQuery(std::move(txn), std::move(sql));
// Note: This mutator might be re-run, or its effects discarded, so
// changing non-transactional state (e.g., by producing output) is,
// in general, not something to be imitated.
for (auto& row : google::cloud::spanner::StreamOf<RowType>(rows)) {
if (!row) return std::move(row).status();
std::cout << "SingerId: " << std::get<0>(*row) << " ";
std::cout << "FullName: " << std::get<1>(*row) << "\n";
}
std::cout << "Deleted row(s) count: " << rows.RowsModified() << "\n";
return google::cloud::spanner::Mutations{};
});
if (!commit) throw std::move(commit).status();
}C#
using Google.Cloud.Spanner.Data;
using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
public class DeleteUsingDmlReturningAsyncSample
{
public async Task<List<string>> DeleteUsingDmlReturningAsync(string projectId, string instanceId, string databaseId)
{
string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";
using var connection = new SpannerConnection(connectionString);
await connection.OpenAsync();
// Delete records from SINGERS table satisfying a
// particular condition and return the SingerId
// and FullName column of the deleted records using
// 'THEN RETURN SingerId, FullName'.
// It is also possible to return all columns of all the
// deleted records by using 'THEN RETURN *'.
using var cmd = connection.CreateDmlCommand("DELETE FROM Singers WHERE FirstName = 'Alice' THEN RETURN SingerId, FullName");
var reader = await cmd.ExecuteReaderAsync();
var deletedSingerNames = new List<string>();
while (await reader.ReadAsync())
{
deletedSingerNames.Add(reader.GetFieldValue<string>("FullName"));
}
Console.WriteLine($"{deletedSingerNames.Count} row(s) deleted...");
return deletedSingerNames;
}
}Go
import (
"context"
"fmt"
"io"
"cloud.google.com/go/spanner"
"google.golang.org/api/iterator"
)
func deleteUsingDMLReturning(w io.Writer, db string) error {
ctx := context.Background()
client, err := spanner.NewClient(ctx, db)
if err != nil {
return err
}
defer client.Close()
// Delete records from SINGERS table satisfying a
// particular condition and returns the SingerId
// and FullName column of the deleted records using
// 'THEN RETURN SingerId, FullName'.
// It is also possible to return all columns of all the
// deleted records by using 'THEN RETURN *'.
_, err = client.ReadWriteTransaction(ctx, func(ctx context.Context, txn *spanner.ReadWriteTransaction) error {
stmt := spanner.Statement{
SQL: `DELETE FROM Singers WHERE FirstName = 'Alice'
THEN RETURN SingerId, FullName`,
}
iter := txn.Query(ctx, stmt)
defer iter.Stop()
for {
row, err := iter.Next()
if err == iterator.Done {
break
}
if err != nil {
return err
}
var (
singerID int64
fullName string
)
if err := row.Columns(&singerID, &fullName); err != nil {
return err
}
fmt.Fprintf(w, "%d %s\n", singerID, fullName)
}
fmt.Fprintf(w, "%d record(s) deleted.\n", iter.RowCount)
return nil
})
return err
}
Java
import com.google.cloud.spanner.DatabaseClient;
import com.google.cloud.spanner.DatabaseId;
import com.google.cloud.spanner.ResultSet;
import com.google.cloud.spanner.Spanner;
import com.google.cloud.spanner.SpannerOptions;
import com.google.cloud.spanner.Statement;
public class DeleteUsingDmlReturningSample {
static void deleteUsingDmlReturningSample() {
// TODO(developer): Replace these variables before running the sample.
final String projectId = "my-project";
final String instanceId = "my-instance";
final String databaseId = "my-database";
deleteUsingDmlReturningSample(projectId, instanceId, databaseId);
}
static void deleteUsingDmlReturningSample(
String projectId, String instanceId, String databaseId) {
try (Spanner spanner =
SpannerOptions.newBuilder()
.setProjectId(projectId)
.build()
.getService()) {
final DatabaseClient dbClient =
spanner.getDatabaseClient(DatabaseId.of(projectId, instanceId, databaseId));
// Delete records from SINGERS table satisfying a
// particular condition and returns the SingerId
// and FullName column of the deleted records using
// ‘THEN RETURN SingerId, FullName’.
// It is also possible to return all columns of all the
// deleted records by using ‘THEN RETURN *’.
dbClient
.readWriteTransaction()
.run(
transaction -> {
String sql =
"DELETE FROM Singers WHERE FirstName = 'Alice' THEN RETURN SingerId, FullName";
// readWriteTransaction.executeQuery(..) API should be used for executing
// DML statements with RETURNING clause.
try (ResultSet resultSet = transaction.executeQuery(Statement.of(sql))) {
while (resultSet.next()) {
System.out.printf("%d %s\n", resultSet.getLong(0), resultSet.getString(1));
}
System.out.printf(
"Deleted row(s) count: %d\n", resultSet.getStats().getRowCountExact());
}
return null;
});
}
}
}Node.js
// Imports the Google Cloud client library.
const {Spanner} = require('@google-cloud/spanner');
/**
* TODO(developer): Uncomment the following lines before running the sample.
*/
// const projectId = 'my-project-id';
// const instanceId = 'my-instance';
// const databaseId = 'my-database';
// Creates a client
const spanner = new Spanner({
projectId: projectId,
});
function deleteUsingDmlReturning(instanceId, databaseId) {
// Gets a reference to a Cloud Spanner instance and database.
const instance = spanner.instance(instanceId);
const database = instance.database(databaseId);
database.runTransaction(async (err, transaction) => {
if (err) {
console.error(err);
return;
}
try {
const [rows, stats] = await transaction.run({
sql: 'DELETE FROM Singers WHERE SingerId = 18 THEN RETURN FullName',
});
const rowCount = Math.floor(stats[stats.rowCount]);
console.log(
`Successfully deleted ${rowCount} record from the Singers table.`
);
rows.forEach(row => {
console.log(row.toJSON().FullName);
});
await transaction.commit();
} catch (err) {
console.error('ERROR:', err);
} finally {
// Close the database when finished.
database.close();
}
});
}
deleteUsingDmlReturning(instanceId, databaseId);PHP
use Google\Cloud\Spanner\SpannerClient;
/**
* Delete data from the given database using DML returning.
*
* @param string $instanceId The Spanner instance ID.
* @param string $databaseId The Spanner database ID.
*/
function delete_dml_returning(string $instanceId, string $databaseId): void
{
$spanner = new SpannerClient();
$instance = $spanner->instance($instanceId);
$database = $instance->database($databaseId);
$transaction = $database->transaction();
// Delete records from SINGERS table satisfying a particular condition and
// returns the SingerId and FullName column of the deleted records using
// 'THEN RETURN SingerId, FullName'. It is also possible to return all columns
// of all the deleted records by using 'THEN RETURN *'.
$result = $transaction->execute(
"DELETE FROM Singers WHERE FirstName = 'Alice' "
. 'THEN RETURN SingerId, FullName',
);
foreach ($result->rows() as $row) {
printf(
'%d %s.' . PHP_EOL,
$row['SingerId'],
$row['FullName']
);
}
printf(
'Deleted row(s) count: %d' . PHP_EOL,
$result->stats()['rowCountExact']
);
$transaction->commit();
}Python
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
# Delete records from SINGERS table satisfying a
# particular condition and returns the SingerId
# and FullName column of the deleted records using
# 'THEN RETURN SingerId, FullName'.
# It is also possible to return all columns of all the
# deleted records by using 'THEN RETURN *'.
def delete_singers(transaction):
results = transaction.execute_sql(
"DELETE FROM Singers WHERE FirstName = 'David' "
"THEN RETURN SingerId, FullName"
)
for result in results:
print("SingerId: {}, FullName: {}".format(*result))
print("{} record(s) deleted.".format(results.stats.row_count_exact))
database.run_in_transaction(delete_singers)Ruby
require "google/cloud/spanner"
##
# This is a snippet for showcasing how to use DML return feature with delete
# operation.
#
# @param project_id [String] The ID of the Google Cloud project.
# @param instance_id [String] The ID of the spanner instance.
# @param database_id [String] The ID of the database.
#
def spanner_delete_dml_returning project_id:, instance_id:, database_id:
spanner = Google::Cloud::Spanner.new project: project_id
client = spanner.client instance_id, database_id
client.transaction do |transaction|
# Delete records from SINGERS table satisfying a particular condition and
# returns the SingerId and FullName column of the deleted records using
# ‘THEN RETURN SingerId, FullName’.
# It is also possible to return all columns of all the deleted records
# by using ‘THEN RETURN *’.
results = transaction.execute_query "DELETE FROM Singers WHERE FirstName = 'Alice' THEN RETURN SingerId, FullName"
results.rows.each do |row|
puts "Deleted singer with SingerId: #{row[:SingerId]}, FullName: #{row[:FullName]}"
end
puts "Deleted row(s) count: #{results.row_count}"
end
end
PostgreSQL
C++
void DeleteUsingDmlReturning(google::cloud::spanner::Client client) {
// Delete records from SINGERS table satisfying a particular condition
// and return the SingerId and FullName column of the deleted records
// using `RETURNING SingerId, FullName'.
auto commit = client.Commit(
[&client](google::cloud::spanner::Transaction txn)
-> google::cloud::StatusOr<google::cloud::spanner::Mutations> {
auto sql = google::cloud::spanner::SqlStatement(R"""(
DELETE FROM Singers
WHERE FirstName = 'Alice'
RETURNING SingerId, FullName
)""");
using RowType = std::tuple<std::int64_t, std::string>;
auto rows = client.ExecuteQuery(std::move(txn), std::move(sql));
for (auto& row : google::cloud::spanner::StreamOf<RowType>(rows)) {
if (!row) return std::move(row).status();
std::cout << "SingerId: " << std::get<0>(*row) << " ";
std::cout << "FullName: " << std::get<1>(*row) << "\n";
}
std::cout << "Deleted row(s) count: " << rows.RowsModified() << "\n";
return google::cloud::spanner::Mutations{};
});
if (!commit) throw std::move(commit).status();
}C#
using Google.Cloud.Spanner.Data;
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
public class DeleteUsingDmlReturningAsyncPostgresSample
{
public async Task<List<string>> DeleteUsingDmlReturningAsyncPostgres(string projectId, string instanceId, string databaseId)
{
string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";
using var connection = new SpannerConnection(connectionString);
await connection.OpenAsync();
// Delete records from SINGERS table satisfying a
// particular condition and return the SingerId
// and FullName column of the deleted records using
// 'RETURNING SingerId, FullName'.
// It is also possible to return all columns of all the
// deleted records by using 'RETURNING *'.
using var cmd = connection.CreateDmlCommand("DELETE FROM Singers WHERE FirstName = 'Lata' RETURNING SingerId, FullName");
var reader = await cmd.ExecuteReaderAsync();
var deletedSingerNames = new List<string>();
while (await reader.ReadAsync())
{
deletedSingerNames.Add(reader.GetFieldValue<string>("fullname"));
}
Console.WriteLine($"{deletedSingerNames.Count} row(s) deleted...");
return deletedSingerNames;
}
}Go
import (
"context"
"fmt"
"io"
"cloud.google.com/go/spanner"
"google.golang.org/api/iterator"
)
func pgDeleteUsingDMLReturning(w io.Writer, db string) error {
ctx := context.Background()
client, err := spanner.NewClient(ctx, db)
if err != nil {
return err
}
defer client.Close()
// Delete records from SINGERS table satisfying a
// particular condition and returns the SingerId
// and FullName column of the deleted records using
// 'RETURNING SingerId, FullName'.
// It is also possible to return all columns of all the
// deleted records by using 'RETURNING *'.
_, err = client.ReadWriteTransaction(ctx, func(ctx context.Context, txn *spanner.ReadWriteTransaction) error {
stmt := spanner.Statement{
SQL: `DELETE FROM Singers WHERE FirstName = 'Alice'
RETURNING SingerId, FullName`,
}
iter := txn.Query(ctx, stmt)
defer iter.Stop()
for {
row, err := iter.Next()
if err == iterator.Done {
break
}
if err != nil {
return err
}
var (
singerID int64
fullName string
)
if err := row.Columns(&singerID, &fullName); err != nil {
return err
}
fmt.Fprintf(w, "%d %s\n", singerID, fullName)
}
fmt.Fprintf(w, "%d record(s) deleted.\n", iter.RowCount)
return nil
})
return err
}
Java
import com.google.cloud.spanner.DatabaseClient;
import com.google.cloud.spanner.DatabaseId;
import com.google.cloud.spanner.ResultSet;
import com.google.cloud.spanner.Spanner;
import com.google.cloud.spanner.SpannerOptions;
import com.google.cloud.spanner.Statement;
public class PgDeleteUsingDmlReturningSample {
static void deleteUsingDmlReturningSample() {
// TODO(developer): Replace these variables before running the sample.
final String projectId = "my-project";
final String instanceId = "my-instance";
final String databaseId = "my-database";
deleteUsingDmlReturningSample(projectId, instanceId, databaseId);
}
static void deleteUsingDmlReturningSample(
String projectId, String instanceId, String databaseId) {
try (Spanner spanner =
SpannerOptions.newBuilder()
.setProjectId(projectId)
.build()
.getService()) {
final DatabaseClient dbClient =
spanner.getDatabaseClient(DatabaseId.of(projectId, instanceId, databaseId));
// Delete records from SINGERS table satisfying a
// particular condition and returns the SingerId
// and FullName column of the deleted records using
// ‘RETURNING SingerId, FullName’.
// It is also possible to return all columns of all the
// deleted records by using ‘RETURNING *’.
dbClient
.readWriteTransaction()
.run(
transaction -> {
String sql =
"DELETE FROM Singers WHERE FirstName = 'Alice' RETURNING SingerId, FullName";
// readWriteTransaction.executeQuery(..) API should be used for executing
// DML statements with RETURNING clause.
try (ResultSet resultSet = transaction.executeQuery(Statement.of(sql))) {
while (resultSet.next()) {
System.out.printf("%d %s\n", resultSet.getLong(0), resultSet.getString(1));
}
System.out.printf(
"Deleted row(s) count: %d\n", resultSet.getStats().getRowCountExact());
}
return null;
});
}
}
}Node.js
// Imports the Google Cloud client library.
const {Spanner} = require('@google-cloud/spanner');
/**
* TODO(developer): Uncomment the following lines before running the sample.
*/
// const projectId = 'my-project-id';
// const instanceId = 'my-instance';
// const databaseId = 'my-database';
// Creates a client
const spanner = new Spanner({
projectId: projectId,
});
function pgDeleteUsingDmlReturning(instanceId, databaseId) {
// Gets a reference to a Cloud Spanner instance and database.
const instance = spanner.instance(instanceId);
const database = instance.database(databaseId);
database.runTransaction(async (err, transaction) => {
if (err) {
console.error(err);
return;
}
try {
const [rows, stats] = await transaction.run({
sql: 'DELETE FROM Singers WHERE SingerId = 18 RETURNING FullName',
});
const rowCount = Math.floor(stats[stats.rowCount]);
console.log(
`Successfully deleted ${rowCount} record from the Singers table.`
);
rows.forEach(row => {
console.log(row.toJSON().fullname);
});
await transaction.commit();
} catch (err) {
console.error('ERROR:', err);
} finally {
// Close the database when finished.
database.close();
}
});
}
pgDeleteUsingDmlReturning(instanceId, databaseId);PHP
use Google\Cloud\Spanner\SpannerClient;
/**
* Delete data from the given postgresql database using DML returning.
*
* @param string $instanceId The Spanner instance ID.
* @param string $databaseId The Spanner database ID.
*/
function pg_delete_dml_returning(string $instanceId, string $databaseId): void
{
$spanner = new SpannerClient();
$instance = $spanner->instance($instanceId);
$database = $instance->database($databaseId);
$transaction = $database->transaction();
// Delete records from SINGERS table satisfying a particular condition and
// returns the SingerId and FullName column of the deleted records using
// ‘RETURNING SingerId, FullName’. It is also possible to return all columns
// of all the deleted records by using ‘RETURNING *’.
$result = $transaction->execute(
"DELETE FROM Singers WHERE FirstName = 'Alice' "
. 'RETURNING SingerId, FullName',
);
foreach ($result->rows() as $row) {
printf(
'%d %s.' . PHP_EOL,
$row['singerid'],
$row['fullname']
);
}
printf(
'Deleted row(s) count: %d' . PHP_EOL,
$result->stats()['rowCountExact']
);
$transaction->commit();
}Python
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
# Delete records from SINGERS table satisfying a
# particular condition and returns the SingerId
# and FullName column of the deleted records using
# 'RETURNING SingerId, FullName'.
# It is also possible to return all columns of all the
# deleted records by using 'RETURNING *'.
def delete_singers(transaction):
results = transaction.execute_sql(
"DELETE FROM Singers WHERE FirstName = 'David' "
"RETURNING SingerId, FullName"
)
for result in results:
print("SingerId: {}, FullName: {}".format(*result))
print("{} record(s) deleted.".format(results.stats.row_count_exact))
database.run_in_transaction(delete_singers)Ruby
require "google/cloud/spanner"
##
# This is a snippet for showcasing how to use DML return feature with delete
# operation in PostgreSql.
#
# @param project_id [String] The ID of the Google Cloud project.
# @param instance_id [String] The ID of the spanner instance.
# @param database_id [String] The ID of the database.
#
def spanner_postgresql_delete_dml_returning project_id:, instance_id:, database_id:
spanner = Google::Cloud::Spanner.new project: project_id
client = spanner.client instance_id, database_id
client.transaction do |transaction|
# Delete records from SINGERS table satisfying a particular condition and
# returns the SingerId and FullName column of the deleted records using
# ‘RETURNING SingerId, FullName’.
# It is also possible to return all columns of all the deleted records
# by using ‘RETURNING *’.
results = transaction.execute_query "DELETE FROM singers WHERE firstname = 'Alice' RETURNING SingerId, FullName"
results.rows.each do |row|
puts "Deleted singer with SingerId: #{row[:singerid]}, FullName: #{row[:fullname]}"
end
puts "Deleted row(s) count: #{results.row_count}"
end
end
读取在同一事务中写入的数据
使用 DML 语句所做的更改对同一事务中的后续语句可见。这与使用变更不同，使用变更所做的更改在事务提交之前不可见。
Spanner 会在每个 DML 语句之后检查约束条件。这与使用变更不同，在变更后，Spanner 会在提交之前缓冲客户端中的变更，并在提交时检查限制条件。在每个语句之后评估限制条件可让 Spanner 保证 DML 语句返回的数据与架构一致。
以下示例更新 Singers 表中的一行，然后执行 SELECT 语句以输出新值。
C++
void DmlWriteThenRead(google::cloud::spanner::Client client) {
namespace spanner = ::google::cloud::spanner;
using ::google::cloud::StatusOr;
auto commit_result = client.Commit(
[&client](spanner::Transaction txn) -> StatusOr<spanner::Mutations> {
auto insert = client.ExecuteDml(
txn, spanner::SqlStatement(
"INSERT INTO Singers (SingerId, FirstName, LastName)"
" VALUES (11, 'Timothy', 'Campbell')"));
if (!insert) return std::move(insert).status();
// Read newly inserted record.
spanner::SqlStatement select(
"SELECT FirstName, LastName FROM Singers where SingerId = 11");
using RowType = std::tuple<std::string, std::string>;
auto rows = client.ExecuteQuery(std::move(txn), std::move(select));
// Note: This mutator might be re-run, or its effects discarded, so
// changing non-transactional state (e.g., by producing output) is,
// in general, not something to be imitated.
for (auto const& row : spanner::StreamOf<RowType>(rows)) {
if (!row) return std::move(row).status();
std::cout << "FirstName: " << std::get<0>(*row) << "\t";
std::cout << "LastName: " << std::get<1>(*row) << "\n";
}
return spanner::Mutations{};
});
if (!commit_result) throw std::move(commit_result).status();
std::cout << "Write then read succeeded [spanner_dml_write_then_read]\n";
}C#
using Google.Cloud.Spanner.Data;
using System;
using System.Threading.Tasks;
public class WriteAndReadUsingDmlCoreAsyncSample
{
public async Task<int> WriteAndReadUsingDmlCoreAsync(string projectId, string instanceId, string databaseId)
{
string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";
using var connection = new SpannerConnection(connectionString);
await connection.OpenAsync();
using var createDmlCmd = connection.CreateDmlCommand(@"INSERT Singers (SingerId, FirstName, LastName) VALUES (11, 'Timothy', 'Campbell')");
int rowCount = await createDmlCmd.ExecuteNonQueryAsync();
Console.WriteLine($"{rowCount} row(s) inserted...");
// Read newly inserted record.
using var createSelectCmd = connection.CreateSelectCommand(@"SELECT FirstName, LastName FROM Singers WHERE SingerId = 11");
using var reader = await createSelectCmd.ExecuteReaderAsync();
while (await reader.ReadAsync())
{
Console.WriteLine($"{reader.GetFieldValue<string>("FirstName")} {reader.GetFieldValue<string>("LastName")}");
}
return rowCount;
}
}Go
import (
"context"
"fmt"
"io"
"cloud.google.com/go/spanner"
"google.golang.org/api/iterator"
)
func writeAndReadUsingDML(w io.Writer, db string) error {
ctx := context.Background()
client, err := spanner.NewClient(ctx, db)
if err != nil {
return err
}
defer client.Close()
_, err = client.ReadWriteTransaction(ctx, func(ctx context.Context, txn *spanner.ReadWriteTransaction) error {
// Insert Record
stmt := spanner.Statement{
SQL: `INSERT Singers (SingerId, FirstName, LastName)
VALUES (11, 'Timothy', 'Campbell')`,
}
rowCount, err := txn.Update(ctx, stmt)
if err != nil {
return err
}
fmt.Fprintf(w, "%d record(s) inserted.\n", rowCount)
// Read newly inserted record
stmt = spanner.Statement{SQL: `SELECT FirstName, LastName FROM Singers WHERE SingerId = 11`}
iter := txn.Query(ctx, stmt)
defer iter.Stop()
for {
row, err := iter.Next()
if err == iterator.Done || err != nil {
break
}
var firstName, lastName string
if err := row.ColumnByName("FirstName", &firstName); err != nil {
return err
}
if err := row.ColumnByName("LastName", &lastName); err != nil {
return err
}
fmt.Fprintf(w, "Found record name with %s, %s", firstName, lastName)
}
return err
})
return err
}
Java
static void writeAndReadUsingDml(DatabaseClient dbClient) {
dbClient
.readWriteTransaction()
.run(transaction -> {
// Insert record.
String sql =
"INSERT INTO Singers (SingerId, FirstName, LastName) "
+ " VALUES (11, 'Timothy', 'Campbell')";
long rowCount = transaction.executeUpdate(Statement.of(sql));
System.out.printf("%d record inserted.\n", rowCount);
// Read newly inserted record.
sql = "SELECT FirstName, LastName FROM Singers WHERE SingerId = 11";
// We use a try-with-resource block to automatically release resources held by
// ResultSet.
try (ResultSet resultSet = transaction.executeQuery(Statement.of(sql))) {
while (resultSet.next()) {
System.out.printf(
"%s %s\n",
resultSet.getString("FirstName"), resultSet.getString("LastName"));
}
}
return null;
});
}Node.js
// Imports the Google Cloud client library
const {Spanner} = require('@google-cloud/spanner');
/**
* TODO(developer): Uncomment the following lines before running the sample.
*/
// const projectId = 'my-project-id';
// const instanceId = 'my-instance';
// const databaseId = 'my-database';
// Creates a client
const spanner = new Spanner({
projectId: projectId,
});
// Gets a reference to a Cloud Spanner instance and database
const instance = spanner.instance(instanceId);
const database = instance.database(databaseId);
database.runTransaction(async (err, transaction) => {
if (err) {
console.error(err);
return;
}
try {
await transaction.runUpdate({
sql: `INSERT Singers (SingerId, FirstName, LastName)
VALUES (11, 'Timothy', 'Campbell')`,
});
const [rows] = await transaction.run({
sql: 'SELECT FirstName, LastName FROM Singers',
});
rows.forEach(row => {
const json = row.toJSON();
console.log(`${json.FirstName} ${json.LastName}`);
});
await transaction.commit();
} catch (err) {
console.error('ERROR:', err);
} finally {
// Close the database when finished.
database.close();
}
});PHP
use Google\Cloud\Spanner\SpannerClient;
use Google\Cloud\Spanner\Transaction;
/**
* Writes then reads data inside a Transaction with a DML statement.
*
* The database and table must already exist and can be created using
* `create_database`.
* Example:
* ```
* insert_data($instanceId, $databaseId);
* ```
*
* @param string $instanceId The Spanner instance ID.
* @param string $databaseId The Spanner database ID.
*/
function write_read_with_dml(string $instanceId, string $databaseId): void
{
$spanner = new SpannerClient();
$instance = $spanner->instance($instanceId);
$database = $instance->database($databaseId);
$database->runTransaction(function (Transaction $t) {
$rowCount = $t->executeUpdate(
'INSERT Singers (SingerId, FirstName, LastName) '
. " VALUES (11, 'Timothy', 'Campbell')");
printf('Inserted %d row(s).' . PHP_EOL, $rowCount);
$results = $t->execute('SELECT FirstName, LastName FROM Singers WHERE SingerId = 11');
foreach ($results as $row) {
printf('%s %s' . PHP_EOL, $row['FirstName'], $row['LastName']);
}
$t->commit();
});
}Python
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
def write_then_read(transaction):
# Insert record.
row_ct = transaction.execute_update(
"INSERT INTO Singers (SingerId, FirstName, LastName) "
" VALUES (11, 'Timothy', 'Campbell')"
)
print("{} record(s) inserted.".format(row_ct))
# Read newly inserted record.
results = transaction.execute_sql(
"SELECT FirstName, LastName FROM Singers WHERE SingerId = 11"
)
for result in results:
print("FirstName: {}, LastName: {}".format(*result))
database.run_in_transaction(write_then_read)Ruby
# project_id = "Your Google Cloud project ID"
# instance_id = "Your Spanner instance ID"
# database_id = "Your Spanner database ID"
require "google/cloud/spanner"
spanner = Google::Cloud::Spanner.new project: project_id
client = spanner.client instance_id, database_id
row_count = 0
client.transaction do |transaction|
row_count = transaction.execute_update(
"INSERT INTO Singers (SingerId, FirstName, LastName) VALUES (11, 'Timothy', 'Campbell')"
)
puts "#{row_count} record updated."
transaction.execute("SELECT FirstName, LastName FROM Singers WHERE SingerId = 11").rows.each do |row|
puts "#{row[:FirstName]} #{row[:LastName]}"
end
end获取查询计划
您可以使用 Google Cloud 控制台、客户端库和 gcloud 命令行工具检索查询计划。
使用分区 DML
分区 DML 专为批量更新和删除而设计，尤其是定期清理和回填。
使用 Google Cloud CLI 执行语句
如需执行分区 DML 语句，请将 gcloud spanner databases execute-sql 命令与 --enable-partitioned-dml 选项结合使用。以下示例更新 Albums 表中的行。
gcloud spanner databases execute-sql example-db \
--instance=test-instance --enable-partitioned-dml \
--sql='UPDATE Albums SET MarketingBudget = 0 WHERE MarketingBudget IS NULL'
使用客户端库修改数据
以下代码示例更新 Albums 表的 MarketingBudget 列。
C++
您可以使用 ExecutePartitionedDml() 函数来执行分区 DML 语句。
void DmlPartitionedUpdate(google::cloud::spanner::Client client) {
namespace spanner = ::google::cloud::spanner;
auto result = client.ExecutePartitionedDml(
spanner::SqlStatement("UPDATE Albums SET MarketingBudget = 100000"
" WHERE SingerId > 1"));
if (!result) throw std::move(result).status();
std::cout << "Updated at least " << result->row_count_lower_bound
<< " row(s) [spanner_dml_partitioned_update]\n";
}C#
使用 ExecutePartitionedUpdateAsync() 方法来执行分区 DML 语句。
using Google.Cloud.Spanner.Data;
using System;
using System.Threading.Tasks;
public class UpdateUsingPartitionedDmlCoreAsyncSample
{
public async Task<long> UpdateUsingPartitionedDmlCoreAsync(string projectId, string instanceId, string databaseId)
{
string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";
using var connection = new SpannerConnection(connectionString);
await connection.OpenAsync();
using var cmd = connection.CreateDmlCommand("UPDATE Albums SET MarketingBudget = 100000 WHERE SingerId > 1");
long rowCount = await cmd.ExecutePartitionedUpdateAsync();
Console.WriteLine($"{rowCount} row(s) updated...");
return rowCount;
}
}Go
使用 PartitionedUpdate() 方法来执行分区 DML 语句。
import (
"context"
"fmt"
"io"
"cloud.google.com/go/spanner"
)
func updateUsingPartitionedDML(w io.Writer, db string) error {
ctx := context.Background()
client, err := spanner.NewClient(ctx, db)
if err != nil {
return err
}
defer client.Close()
stmt := spanner.Statement{SQL: "UPDATE Albums SET MarketingBudget = 100000 WHERE SingerId > 1"}
rowCount, err := client.PartitionedUpdate(ctx, stmt)
if err != nil {
return err
}
fmt.Fprintf(w, "%d record(s) updated.\n", rowCount)
return nil
}
Java
使用 executePartitionedUpdate() 方法来执行分区 DML 语句。
static void updateUsingPartitionedDml(DatabaseClient dbClient) {
String sql = "UPDATE Albums SET MarketingBudget = 100000 WHERE SingerId > 1";
long rowCount = dbClient.executePartitionedUpdate(Statement.of(sql));
System.out.printf("%d records updated.\n", rowCount);
}Node.js
使用 runPartitionedUpdate() 方法来执行分区 DML 语句。
// Imports the Google Cloud client library
const {Spanner} = require('@google-cloud/spanner');
/**
* TODO(developer): Uncomment the following lines before running the sample.
*/
// const projectId = 'my-project-id';
// const instanceId = 'my-instance';
// const databaseId = 'my-database';
// Creates a client
const spanner = new Spanner({
projectId: projectId,
});
// Gets a reference to a Cloud Spanner instance and database
const instance = spanner.instance(instanceId);
const database = instance.database(databaseId);
try {
const [rowCount] = await database.runPartitionedUpdate({
sql: 'UPDATE Albums SET MarketingBudget = 100000 WHERE SingerId > 1',
});
console.log(`Successfully updated ${rowCount} records.`);
} catch (err) {
console.error('ERROR:', err);
} finally {
// Close the database when finished.
database.close();
}PHP
使用 executePartitionedUpdate() 方法来执行分区 DML 语句。
use Google\Cloud\Spanner\SpannerClient;
/**
* Updates sample data in the database by partition with a DML statement.
*
* This updates the `MarketingBudget` column which must be created before
* running this sample. You can add the column by running the `add_column`
* sample or by running this DDL statement against your database:
*
* ALTER TABLE Albums ADD COLUMN MarketingBudget INT64
*
* Example:
* ```
* update_data($instanceId, $databaseId);
* ```
*
* @param string $instanceId The Spanner instance ID.
* @param string $databaseId The Spanner database ID.
*/
function update_data_with_partitioned_dml(string $instanceId, string $databaseId): void
{
$spanner = new SpannerClient();
$instance = $spanner->instance($instanceId);
$database = $instance->database($databaseId);
$rowCount = $database->executePartitionedUpdate(
'UPDATE Albums SET MarketingBudget = 100000 WHERE SingerId > 1'
);
printf('Updated %d row(s).' . PHP_EOL, $rowCount);
}Python
使用 execute_partitioned_dml() 方法来执行分区 DML 语句。
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
row_ct = database.execute_partitioned_dml(
"UPDATE Albums SET MarketingBudget = 100000 WHERE SingerId > 1"
)
print("{} records updated.".format(row_ct))Ruby
使用 execute_partitioned_update() 方法来执行分区 DML 语句。
# project_id = "Your Google Cloud project ID"
# instance_id = "Your Spanner instance ID"
# database_id = "Your Spanner database ID"
require "google/cloud/spanner"
spanner = Google::Cloud::Spanner.new project: project_id
client = spanner.client instance_id, database_id
row_count = client.execute_partition_update(
"UPDATE Albums SET MarketingBudget = 100000 WHERE SingerId > 1"
)
puts "#{row_count} records updated."以下代码示例根据 SingerId 列从 Singers 表中删除行。
C++
void DmlPartitionedDelete(google::cloud::spanner::Client client) {
namespace spanner = ::google::cloud::spanner;
auto result = client.ExecutePartitionedDml(
spanner::SqlStatement("DELETE FROM Singers WHERE SingerId > 10"));
if (!result) throw std::move(result).status();
std::cout << "Deleted at least " << result->row_count_lower_bound
<< " row(s) [spanner_dml_partitioned_delete]\n";
}C#
using Google.Cloud.Spanner.Data;
using System;
using System.Threading.Tasks;
public class DeleteUsingPartitionedDmlCoreAsyncSample
{
public async Task<long> DeleteUsingPartitionedDmlCoreAsync(string projectId, string instanceId, string databaseId)
{
string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";
using var connection = new SpannerConnection(connectionString);
await connection.OpenAsync();
using var cmd = connection.CreateDmlCommand("DELETE FROM Singers WHERE SingerId > 10");
long rowCount = await cmd.ExecutePartitionedUpdateAsync();
Console.WriteLine($"{rowCount} row(s) deleted...");
return rowCount;
}
}Go
import (
"context"
"fmt"
"io"
"cloud.google.com/go/spanner"
)
func deleteUsingPartitionedDML(w io.Writer, db string) error {
ctx := context.Background()
client, err := spanner.NewClient(ctx, db)
if err != nil {
return err
}
defer client.Close()
stmt := spanner.Statement{SQL: "DELETE FROM Singers WHERE SingerId > 10"}
rowCount, err := client.PartitionedUpdate(ctx, stmt)
if err != nil {
return err
}
fmt.Fprintf(w, "%d record(s) deleted.", rowCount)
return nil
}
Java
static void deleteUsingPartitionedDml(DatabaseClient dbClient) {
String sql = "DELETE FROM Singers WHERE SingerId > 10";
long rowCount = dbClient.executePartitionedUpdate(Statement.of(sql));
System.out.printf("%d records deleted.\n", rowCount);
}Node.js
// Imports the Google Cloud client library
const {Spanner} = require('@google-cloud/spanner');
/**
* TODO(developer): Uncomment the following lines before running the sample.
*/
// const projectId = 'my-project-id';
// const instanceId = 'my-instance';
// const databaseId = 'my-database';
// Creates a client
const spanner = new Spanner({
projectId: projectId,
});
// Gets a reference to a Cloud Spanner instance and database
const instance = spanner.instance(instanceId);
const database = instance.database(databaseId);
try {
const [rowCount] = await database.runPartitionedUpdate({
sql: 'DELETE FROM Singers WHERE SingerId > 10',
});
console.log(`Successfully deleted ${rowCount} records.`);
} catch (err) {
console.error('ERROR:', err);
} finally {
// Close the database when finished.
database.close();
}PHP
use Google\Cloud\Spanner\SpannerClient;
/**
* Delete sample data in the database by partition with a DML statement.
*
* This updates the `MarketingBudget` column which must be created before
* running this sample. You can add the column by running the `add_column`
* sample or by running this DDL statement against your database:
*
* ALTER TABLE Albums ADD COLUMN MarketingBudget INT64
*
* Example:
* ```
* update_data($instanceId, $databaseId);
* ```
*
* @param string $instanceId The Spanner instance ID.
* @param string $databaseId The Spanner database ID.
*/
function delete_data_with_partitioned_dml(string $instanceId, string $databaseId): void
{
$spanner = new SpannerClient();
$instance = $spanner->instance($instanceId);
$database = $instance->database($databaseId);
$rowCount = $database->executePartitionedUpdate(
'DELETE FROM Singers WHERE SingerId > 10'
);
printf('Deleted %d row(s).' . PHP_EOL, $rowCount);
}Python
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
row_ct = database.execute_partitioned_dml("DELETE FROM Singers WHERE SingerId > 10")
print("{} record(s) deleted.".format(row_ct))Ruby
# project_id = "Your Google Cloud project ID"
# instance_id = "Your Spanner instance ID"
# database_id = "Your Spanner database ID"
require "google/cloud/spanner"
spanner = Google::Cloud::Spanner.new project: project_id
client = spanner.client instance_id, database_id
row_count = client.execute_partition_update(
"DELETE FROM Singers WHERE SingerId > 10"
)
puts "#{row_count} records deleted."使用批量 DML
如果需要避免多个串行请求引起的额外延迟，请使用批处理 DML 在单个事务中发送多个 INSERT、UPDATE 或 DELETE 语句：
C++
使用 ExecuteBatchDml() 函数来执行 DML 语句列表。
void DmlBatchUpdate(google::cloud::spanner::Client client) {
namespace spanner = ::google::cloud::spanner;
auto commit_result =
client.Commit([&client](spanner::Transaction const& txn)
-> google::cloud::StatusOr<spanner::Mutations> {
std::vector<spanner::SqlStatement> statements = {
spanner::SqlStatement("INSERT INTO Albums"
" (SingerId, AlbumId, AlbumTitle,"
" MarketingBudget)"
" VALUES (1, 3, 'Test Album Title', 10000)"),
spanner::SqlStatement("UPDATE Albums"
" SET MarketingBudget = MarketingBudget * 2"
" WHERE SingerId = 1 and AlbumId = 3")};
auto result = client.ExecuteBatchDml(txn, statements);
if (!result) return std::move(result).status();
// Note: This mutator might be re-run, or its effects discarded, so
// changing non-transactional state (e.g., by producing output) is,
// in general, not something to be imitated.
for (std::size_t i = 0; i < result->stats.size(); ++i) {
std::cout << result->stats[i].row_count << " rows affected"
<< " for the statement " << (i + 1) << ".\n";
}
// Batch operations may have partial failures, in which case
// ExecuteBatchDml returns with success, but the application should
// verify that all statements completed successfully
if (!result->status.ok()) return result->status;
return spanner::Mutations{};
});
if (!commit_result) throw std::move(commit_result).status();
std::cout << "Update was successful [spanner_dml_batch_update]\n";
}C#
使用 connection.CreateBatchDmlCommand() 方法创建批处理命令，使用 Add 方法添加 DML 语句，然后使用 ExecuteNonQueryAsync() 方法执行该语句。
using Google.Cloud.Spanner.Data;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
public class UpdateUsingBatchDmlCoreAsyncSample
{
public async Task<int> UpdateUsingBatchDmlCoreAsync(string projectId, string instanceId, string databaseId)
{
string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";
using var connection = new SpannerConnection(connectionString);
await connection.OpenAsync();
SpannerBatchCommand cmd = connection.CreateBatchDmlCommand();
cmd.Add("INSERT INTO Albums (SingerId, AlbumId, AlbumTitle, MarketingBudget) VALUES (1, 3, 'Test Album Title', 10000)");
cmd.Add("UPDATE Albums SET MarketingBudget = MarketingBudget * 2 WHERE SingerId = 1 and AlbumId = 3");
IEnumerable<long> affectedRows = await cmd.ExecuteNonQueryAsync();
Console.WriteLine($"Executed {affectedRows.Count()} " + "SQL statements using Batch DML.");
return affectedRows.Count();
}
}Go
使用 BatchUpdate() 方法来执行一组 DML Statement 对象。
import (
"context"
"fmt"
"io"
"cloud.google.com/go/spanner"
)
func updateUsingBatchDML(w io.Writer, db string) error {
ctx := context.Background()
client, err := spanner.NewClient(ctx, db)
if err != nil {
return err
}
defer client.Close()
_, err = client.ReadWriteTransaction(ctx, func(ctx context.Context, txn *spanner.ReadWriteTransaction) error {
stmts := []spanner.Statement{
{SQL: `INSERT INTO Albums
(SingerId, AlbumId, AlbumTitle, MarketingBudget)
VALUES (1, 3, 'Test Album Title', 10000)`},
{SQL: `UPDATE Albums
SET MarketingBudget = MarketingBudget * 2
WHERE SingerId = 1 and AlbumId = 3`},
}
rowCounts, err := txn.BatchUpdate(ctx, stmts)
if err != nil {
return err
}
fmt.Fprintf(w, "Executed %d SQL statements using Batch DML.\n", len(rowCounts))
return nil
})
return err
}
Java
使用 transaction.batchUpdate() 方法来执行多个 DML Statement 对象的 ArrayList。
static void updateUsingBatchDml(DatabaseClient dbClient) {
dbClient
.readWriteTransaction()
.run(transaction -> {
List<Statement> stmts = new ArrayList<Statement>();
String sql =
"INSERT INTO Albums "
+ "(SingerId, AlbumId, AlbumTitle, MarketingBudget) "
+ "VALUES (1, 3, 'Test Album Title', 10000) ";
stmts.add(Statement.of(sql));
sql =
"UPDATE Albums "
+ "SET MarketingBudget = MarketingBudget * 2 "
+ "WHERE SingerId = 1 and AlbumId = 3";
stmts.add(Statement.of(sql));
long[] rowCounts;
try {
rowCounts = transaction.batchUpdate(stmts);
} catch (SpannerBatchUpdateException e) {
rowCounts = e.getUpdateCounts();
}
for (int i = 0; i < rowCounts.length; i++) {
System.out.printf("%d record updated by stmt %d.\n", rowCounts[i], i);
}
return null;
});
}Node.js
使用 transaction.batchUpdate() 来执行 DML 语句列表。
// Imports the Google Cloud client library
const {Spanner} = require('@google-cloud/spanner');
/**
* TODO(developer): Uncomment the following lines before running the sample.
*/
// const projectId = 'my-project-id';
// const instanceId = 'my-instance';
// const databaseId = 'my-database';
// Creates a client
const spanner = new Spanner({
projectId: projectId,
});
// Gets a reference to a Cloud Spanner instance and database
const instance = spanner.instance(instanceId);
const database = instance.database(databaseId);
const insert = {
sql: `INSERT INTO Albums (SingerId, AlbumId, AlbumTitle, MarketingBudget)
VALUES (1, 3, "Test Album Title", 10000)`,
};
const update = {
sql: `UPDATE Albums SET MarketingBudget = MarketingBudget * 2
WHERE SingerId = 1 and AlbumId = 3`,
};
const dmlStatements = [insert, update];
try {
await database.runTransactionAsync(async transaction => {
const [rowCounts] = await transaction.batchUpdate(dmlStatements);
await transaction.commit();
console.log(
`Successfully executed ${rowCounts.length} SQL statements using Batch DML.`
);
});
} catch (err) {
console.error('ERROR:', err);
throw err;
} finally {
// Close the database when finished.
database.close();
}PHP
使用 executeUpdateBatch() 创建 DML 语句列表，然后使用 commit() 执行该语句。
use Google\Cloud\Spanner\SpannerClient;
use Google\Cloud\Spanner\Transaction;
/**
* Updates sample data in the database with Batch DML.
*
* This requires the `MarketingBudget` column which must be created before
* running this sample. You can add the column by running the `add_column`
* sample or by running this DDL statement against your database:
*
* ALTER TABLE Albums ADD COLUMN MarketingBudget INT64
*
* Example:
* ```
* update_data_with_batch_dml($instanceId, $databaseId);
* ```
*
* @param string $instanceId The Spanner instance ID.
* @param string $databaseId The Spanner database ID.
*/
function update_data_with_batch_dml(string $instanceId, string $databaseId): void
{
$spanner = new SpannerClient();
$instance = $spanner->instance($instanceId);
$database = $instance->database($databaseId);
$batchDmlResult = $database->runTransaction(function (Transaction $t) {
$result = $t->executeUpdateBatch([
[
'sql' => 'INSERT INTO Albums '
. '(SingerId, AlbumId, AlbumTitle, MarketingBudget) '
. "VALUES (1, 3, 'Test Album Title', 10000)"
],
[
'sql' => 'UPDATE Albums '
. 'SET MarketingBudget = MarketingBudget * 2 '
. 'WHERE SingerId = 1 and AlbumId = 3'
],
]);
$t->commit();
$rowCounts = count($result->rowCounts());
printf('Executed %s SQL statements using Batch DML.' . PHP_EOL,
$rowCounts);
});
}Python
使用 transaction.batch_update() 来执行多个 DML 语句字符串。
from google.rpc.code_pb2 import OK
# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
insert_statement = (
"INSERT INTO Albums "
"(SingerId, AlbumId, AlbumTitle, MarketingBudget) "
"VALUES (1, 3, 'Test Album Title', 10000)"
)
update_statement = (
"UPDATE Albums "
"SET MarketingBudget = MarketingBudget * 2 "
"WHERE SingerId = 1 and AlbumId = 3"
)
def update_albums(transaction):
status, row_cts = transaction.batch_update([insert_statement, update_statement])
if status.code != OK:
# Do handling here.
# Note: the exception will still be raised when
# `commit` is called by `run_in_transaction`.
return
print("Executed {} SQL statements using Batch DML.".format(len(row_cts)))
database.run_in_transaction(update_albums)Ruby
使用 transaction.batch_update 来执行多个 DML 语句字符串。
# project_id = "Your Google Cloud project ID"
# instance_id = "Your Spanner instance ID"
# database_id = "Your Spanner database ID"
require "google/cloud/spanner"
spanner = Google::Cloud::Spanner.new project: project_id
client = spanner.client instance_id, database_id
row_counts = nil
client.transaction do |transaction|
row_counts = transaction.batch_update do |b|
b.batch_update(
"INSERT INTO Albums " \
"(SingerId, AlbumId, AlbumTitle, MarketingBudget) " \
"VALUES (1, 3, 'Test Album Title', 10000)"
)
b.batch_update(
"UPDATE Albums " \
"SET MarketingBudget = MarketingBudget * 2 " \
"WHERE SingerId = 1 and AlbumId = 3"
)
end
end
statement_count = row_counts.count
puts "Executed #{statement_count} SQL statements using Batch DML."