删除表中的各个行。
深入探索
如需查看包含此代码示例的详细文档，请参阅以下内容：
代码示例
C++
如需了解如何安装和使用 Spanner 客户端库，请参阅 Spanner 客户端库。
如需向 Spanner 进行身份验证，请设置应用默认凭据。如需了解详情，请参阅为本地开发环境设置身份验证。
void DeleteData(google::cloud::spanner::Client client) {
namespace spanner = ::google::cloud::spanner;
// Delete the albums with key (2,1) and (2,3).
//! [make-key] [keyset-add-key]
auto delete_albums = spanner::DeleteMutationBuilder(
"Albums", spanner::KeySet()
.AddKey(spanner::MakeKey(2, 1))
.AddKey(spanner::MakeKey(2, 3)))
.Build();
//! [make-key] [keyset-add-key]
// Delete some singers using the keys in the range [3, 5]
//! [make-keybound-closed]
auto delete_singers_range =
spanner::DeleteMutationBuilder(
"Singers", spanner::KeySet().AddRange(spanner::MakeKeyBoundClosed(3),
spanner::MakeKeyBoundOpen(5)))
.Build();
//! [make-keybound-closed]
// Deletes remaining rows from the Singers table and the Albums table, because
// the Albums table is defined with ON DELETE CASCADE.
auto delete_singers_all =
spanner::MakeDeleteMutation("Singers", spanner::KeySet::All());
auto commit_result = client.Commit(spanner::Mutations{
delete_albums, delete_singers_range, delete_singers_all});
if (!commit_result) throw std::move(commit_result).status();
std::cout << "Delete was successful [spanner_delete_data]\n";
}C#
如需了解如何安装和使用 Spanner 客户端库，请参阅 Spanner 客户端库。
如需向 Spanner 进行身份验证，请设置应用默认凭据。如需了解详情，请参阅为本地开发环境设置身份验证。
using Google.Cloud.Spanner.Data;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
public class DeleteDataAsyncSample
{
public class Album
{
public int SingerId { get; set; }
public int AlbumId { get; set; }
public string AlbumTitle { get; set; }
}
public async Task<int> DeleteDataAsync(string projectId, string instanceId, string databaseId)
{
string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";
var albums = new List<Album>
{
new Album { SingerId = 2, AlbumId = 1, AlbumTitle = "Green" },
new Album { SingerId = 2, AlbumId = 3, AlbumTitle = "Terrified" },
};
int rowCount = 0;
using (var connection = new SpannerConnection(connectionString))
{
await connection.OpenAsync();
// Delete individual rows from the Albums table.
await Task.WhenAll(albums.Select(async album =>
{
var cmd = connection.CreateDeleteCommand("Albums", new SpannerParameterCollection
{
{ "SingerId", SpannerDbType.Int64, album.SingerId },
{ "AlbumId", SpannerDbType.Int64, album.AlbumId }
});
rowCount += await cmd.ExecuteNonQueryAsync();
}));
Console.WriteLine("Deleted individual rows in Albums.");
// Delete a range of rows from the Singers table where the column key is >=3 and <5.
var cmd = connection.CreateDmlCommand("DELETE FROM Singers WHERE SingerId >= 3 AND SingerId < 5");
rowCount += await cmd.ExecuteNonQueryAsync();
Console.WriteLine($"{rowCount} row(s) deleted from Singers.");
// Delete remaining Singers rows, which will also delete the remaining
// Albums rows since it was defined with ON DELETE CASCADE.
cmd = connection.CreateDmlCommand("DELETE FROM Singers WHERE true");
rowCount += await cmd.ExecuteNonQueryAsync();
Console.WriteLine($"{rowCount} row(s) deleted from Singers.");
}
return rowCount;
}
}Go
如需了解如何安装和使用 Spanner 客户端库，请参阅 Spanner 客户端库。
如需向 Spanner 进行身份验证，请设置应用默认凭据。如需了解详情，请参阅为本地开发环境设置身份验证。
import (
"context"
"io"
"cloud.google.com/go/spanner"
)
func delete(w io.Writer, db string) error {
ctx := context.Background()
client, err := spanner.NewClient(ctx, db)
if err != nil {
return err
}
defer client.Close()
m := []*spanner.Mutation{
// spanner.Key can be used to delete a specific set of rows.
// Delete the Albums with the key values (2,1) and (2,3).
spanner.Delete("Albums", spanner.Key{2, 1}),
spanner.Delete("Albums", spanner.Key{2, 3}),
// spanner.KeyRange can be used to delete rows with a key in a specific range.
// Delete a range of rows where the column key is >=3 and <5
spanner.Delete("Singers", spanner.KeyRange{Start: spanner.Key{3}, End: spanner.Key{5}, Kind: spanner.ClosedOpen}),
// spanner.AllKeys can be used to delete all the rows in a table.
// Delete remaining Singers rows, which will also delete the remaining Albums rows since it was
// defined with ON DELETE CASCADE.
spanner.Delete("Singers", spanner.AllKeys()),
}
_, err = client.Apply(ctx, m)
return err
}
Java
如需了解如何安装和使用 Spanner 客户端库，请参阅 Spanner 客户端库。
如需向 Spanner 进行身份验证，请设置应用默认凭据。如需了解详情，请参阅为本地开发环境设置身份验证。
static void deleteExampleData(DatabaseClient dbClient) {
List<Mutation> mutations = new ArrayList<>();
// KeySet.Builder can be used to delete a specific set of rows.
// Delete the Albums with the key values (2,1) and (2,3).
mutations.add(
Mutation.delete(
"Albums", KeySet.newBuilder().addKey(Key.of(2, 1)).addKey(Key.of(2, 3)).build()));
// KeyRange can be used to delete rows with a key in a specific range.
// Delete a range of rows where the column key is >=3 and <5
mutations.add(
Mutation.delete("Singers", KeySet.range(KeyRange.closedOpen(Key.of(3), Key.of(5)))));
// KeySet.all() can be used to delete all the rows in a table.
// Delete remaining Singers rows, which will also delete the remaining Albums rows since it was
// defined with ON DELETE CASCADE.
mutations.add(Mutation.delete("Singers", KeySet.all()));
dbClient.write(mutations);
System.out.printf("Records deleted.\n");
}Node.js
如需了解如何安装和使用 Spanner 客户端库，请参阅 Spanner 客户端库。
如需向 Spanner 进行身份验证，请设置应用默认凭据。如需了解详情，请参阅为本地开发环境设置身份验证。
// 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);
// Instantiate Spanner table object
const albumsTable = database.table('Albums');
// Deletes individual rows from the Albums table.
try {
const keys = [
[2, 1],
[2, 3],
];
await albumsTable.deleteRows(keys);
console.log('Deleted individual rows in Albums.');
} catch (err) {
console.error('ERROR:', err);
}
// Delete a range of rows where the column key is >=3 and <5
database.runTransaction(async (err, transaction) => {
if (err) {
console.error(err);
return;
}
try {
const [rowCount] = await transaction.runUpdate({
sql: 'DELETE FROM Singers WHERE SingerId >= 3 AND SingerId < 5',
});
console.log(`${rowCount} records deleted from Singers.`);
} catch (err) {
console.error('ERROR:', err);
}
// Deletes remaining rows from the Singers table and the Albums table,
// because Albums table is defined with ON DELETE CASCADE.
try {
// The WHERE clause is required for DELETE statements to prevent
// accidentally deleting all rows in a table.
// https://cloud.google.com/spanner/docs/dml-syntax#where_clause
const [rowCount] = await transaction.runUpdate({
sql: 'DELETE FROM Singers WHERE true',
});
console.log(`${rowCount} records deleted from Singers.`);
await transaction.commit();
} catch (err) {
console.error('ERROR:', err);
} finally {
// Close the database when finished.
await database.close();
}
});PHP
如需了解如何安装和使用 Spanner 客户端库，请参阅 Spanner 客户端库。
如需向 Spanner 进行身份验证，请设置应用默认凭据。如需了解详情，请参阅为本地开发环境设置身份验证。
use Google\Cloud\Spanner\SpannerClient;
use Google\Cloud\Spanner\KeyRange;
use Google\Cloud\Core\Exception\GoogleException;
/**
* Deletes sample data from the given database.
*
* @param string $instanceId The Spanner instance ID.
* @param string $databaseId The Spanner database ID.
* @throws GoogleException
*/
function delete_data(string $instanceId, string $databaseId): void
{
$spanner = new SpannerClient();
$instance = $spanner->instance($instanceId);
$database = $instance->database($databaseId);
// Delete individual rows
$albumsToDelete = $spanner->keySet([
'keys' => [[2, 1], [2, 3]]
]);
$database->delete('Albums', $albumsToDelete);
// Delete a range of rows where the column key is >=3 and <5
// NOTE: A KeyRange must include a start and end.
// NOTE: startType and endType both default to KeyRange::TYPE_OPEN.
$singersRange = $spanner->keyRange([
'startType' => KeyRange::TYPE_CLOSED,
'start' => [3],
'endType' => KeyRange::TYPE_OPEN,
'end' => [5]
]);
$singersToDelete = $spanner->keySet([
'ranges' => [$singersRange]
]);
$database->delete('Singers', $singersToDelete);
// Delete remaining Singers rows, which will also delete the remaining
// Albums rows because Albums was defined with ON DELETE CASCADE
$remainingSingers = $spanner->keySet([
'all' => true
]);
$database->delete('Singers', $remainingSingers);
print('Deleted data.' . PHP_EOL);
}Python
如需了解如何安装和使用 Spanner 客户端库，请参阅 Spanner 客户端库。
如需向 Spanner 进行身份验证，请设置应用默认凭据。如需了解详情，请参阅为本地开发环境设置身份验证。
def delete_data(instance_id, database_id):
"""Deletes sample data from the given database.
The database, table, and data must already exist and can be created using
`create_database` and `insert_data`.
"""
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)
# Delete individual rows
albums_to_delete = spanner.KeySet(keys=[[2, 1], [2, 3]])
# Delete a range of rows where the column key is >=3 and <5
singers_range = spanner.KeyRange(start_closed=[3], end_open=[5])
singers_to_delete = spanner.KeySet(ranges=[singers_range])
# Delete remaining Singers rows, which will also delete the remaining
# Albums rows because Albums was defined with ON DELETE CASCADE
remaining_singers = spanner.KeySet(all_=True)
with database.batch() as batch:
batch.delete("Albums", albums_to_delete)
batch.delete("Singers", singers_to_delete)
batch.delete("Singers", remaining_singers)
print("Deleted data.")
Ruby
如需了解如何安装和使用 Spanner 客户端库，请参阅 Spanner 客户端库。
如需向 Spanner 进行身份验证，请设置应用默认凭据。如需了解详情，请参阅为本地开发环境设置身份验证。
# 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
# Delete individual rows
client.delete "Albums", [[2, 1], [2, 3]]
# Delete a range of rows where the column key is >=3 and <5
key_range = client.range 3, 5, exclude_end: true
client.delete "Singers", key_range
# Delete remaining Singers rows, which will also delete the remaining
# Albums rows because Albums was defined with ON DELETE CASCADE
client.delete "Singers"
后续步骤
如需搜索和过滤其他 Google Cloud 产品的代码示例，请参阅 Google Cloud 示例浏览器。