添加列

通过添加列来更新架构。

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 AddColumn(google::cloud::spanner_admin::DatabaseAdminClient client,
               std::string const& project_id, std::string const& instance_id,
               std::string const& database_id) {
  google::cloud::spanner::Database database(project_id, instance_id,
                                            database_id);
  auto metadata =
      client
          .UpdateDatabaseDdl(
              database.FullName(),
              {"ALTER TABLE Albums ADD COLUMN MarketingBudget INT64"})
          .get();
  google::cloud::spanner_testing::LogUpdateDatabaseDdl(  //! TODO(#4758)
      client, database, metadata.status());              //! TODO(#4758)
  if (!metadata) throw std::move(metadata).status();
  std::cout << "Added MarketingBudget column\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.Threading.Tasks;

public class AddColumnAsyncSample
{
    public async Task AddColumnAsync(string projectId, string instanceId, string databaseId)
    {
        string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";
        string alterStatement = "ALTER TABLE Albums ADD COLUMN MarketingBudget INT64";

        using var connection = new SpannerConnection(connectionString);
        using var updateCmd = connection.CreateDdlCommand(alterStatement);
        await updateCmd.ExecuteNonQueryAsync();
        Console.WriteLine("Added the MarketingBudget column.");
    }
}

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"
	"fmt"
	"io"

	database "cloud.google.com/go/spanner/admin/database/apiv1"
	adminpb "google.golang.org/genproto/googleapis/spanner/admin/database/v1"
)

func addNewColumn(ctx context.Context, w io.Writer, db string) error {
	adminClient, err := database.NewDatabaseAdminClient(ctx)
	if err != nil {
		return err
	}
	defer adminClient.Close()

	op, err := adminClient.UpdateDatabaseDdl(ctx, &adminpb.UpdateDatabaseDdlRequest{
		Database: db,
		Statements: []string{
			"ALTER TABLE Albums ADD COLUMN MarketingBudget INT64",
		},
	})
	if err != nil {
		return err
	}
	if err := op.Wait(ctx); err != nil {
		return err
	}
	fmt.Fprintf(w, "Added MarketingBudget column\n")
	return nil
}

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 addColumn(
    final String project,
    final String instance,
    final String database,
    final Properties properties) throws SQLException {
  try (Connection connection =
      DriverManager.getConnection(
          String.format(
              "jdbc:cloudspanner:/projects/%s/instances/%s/databases/%s",
              project, instance, database),
          properties)) {
    connection
        .createStatement()
        .execute("ALTER TABLE Albums ADD COLUMN MarketingBudget INT64");
    System.out.println("Added MarketingBudget column");
  }
}

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。 


/**
 * TODO(developer): Uncomment the following lines before running the sample.
 */
// const projectId = 'my-project-id';
// const instanceId = 'my-instance';
// const databaseId = 'my-database';

// Imports the Google Cloud client library
const {Spanner} = require('@google-cloud/spanner');

// creates a client
const spanner = new Spanner({
  projectId: projectId,
});

const databaseAdminClient = spanner.getDatabaseAdminClient();

// Creates a new index in the database
try {
  const [operation] = await databaseAdminClient.updateDatabaseDdl({
    database: databaseAdminClient.databasePath(
      projectId,
      instanceId,
      databaseId
    ),
    statements: ['ALTER TABLE Albums ADD COLUMN MarketingBudget INT64'],
  });

  console.log('Waiting for operation to complete...');
  await operation.promise();

  console.log('Added the MarketingBudget column.');
} catch (err) {
  console.error('ERROR:', err);
} finally {
  // Close the spanner client when finished.
  // The databaseAdminClient does not require explicit closure. The closure of the Spanner client will automatically close the databaseAdminClient.
  spanner.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\Admin\Database\V1\Client\DatabaseAdminClient;
use Google\Cloud\Spanner\Admin\Database\V1\UpdateDatabaseDdlRequest;

/**
 * Adds a new column to the Albums table in the example database.
 * Example:
 * ```
 * add_column($projectId, $instanceId, $databaseId);
 * ```
 *
 * @param string $projectId The Google Cloud project ID.
 * @param string $instanceId The Spanner instance ID.
 * @param string $databaseId The Spanner database ID.
 */
function add_column(string $projectId, string $instanceId, string $databaseId): void
{
    $databaseAdminClient = new DatabaseAdminClient();
    $databaseName = DatabaseAdminClient::databaseName($projectId, $instanceId, $databaseId);

    $request = new UpdateDatabaseDdlRequest([
        'database' => $databaseName,
        'statements' => ['ALTER TABLE Albums ADD COLUMN MarketingBudget INT64']
    ]);

    $operation = $databaseAdminClient->updateDatabaseDdl($request);

    print('Waiting for operation to complete...' . PHP_EOL);
    $operation->pollUntilComplete();

    printf('Added the MarketingBudget column.' . 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 add_column(instance_id, database_id):
    """Adds a new column to the Albums table in the example database."""

    from google.cloud.spanner_admin_database_v1.types import \
        spanner_database_admin

    spanner_client = spanner.Client()
    database_admin_api = spanner_client.database_admin_api

    request = spanner_database_admin.UpdateDatabaseDdlRequest(
        database=database_admin_api.database_path(
            spanner_client.project, instance_id, database_id
        ),
        statements=[
            "ALTER TABLE Albums ADD COLUMN MarketingBudget INT64",
        ],
    )

    operation = database_admin_api.update_database_ddl(request)

    print("Waiting for operation to complete...")
    operation.result(OPERATION_TIMEOUT_SECONDS)
    print("Added the MarketingBudget column.")

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"
require "google/cloud/spanner/admin/database"

database_admin_client = Google::Cloud::Spanner::Admin::Database.database_admin

db_path = database_admin_client.database_path project: project_id,
                                              instance: instance_id,
                                              database: database_id

job = database_admin_client.update_database_ddl database: db_path,
                                                statements: [
                                                  "ALTER TABLE Albums ADD COLUMN MarketingBudget INT64"
                                                ]

puts "Waiting for database update to complete"

job.wait_until_done!

puts "Added the MarketingBudget column"

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。