Insérer, mettre à jour et supprimer des données à l'aide de mutations

Cette page explique comment insérer, mettre à jour et supprimer des données en utilisant des mutations. Une mutation représente une séquence d'opérations (insertions, mises à jour, et suppressions) que Cloud Spanner applique de manière atomique à différentes lignes et tables d'une base de données Cloud Spanner.

Même si vous pouvez effectuer un commit des mutations à l'aide de gRPC ou de REST, il est plus courant d'accéder aux API via les bibliothèques clientes.

Cette page présente les tâches de base permettant d'insérer, de mettre à jour et de supprimer des données. Vous trouverez plus d'exemples dans les tutoriels de prise en main.

Insérer des lignes dans une table

C++

Vous pouvez écrire des données à l'aide de la fonction InsertMutationBuilder(). Client::Commit() ajoute des lignes à une table. Toutes les insertions d'un même lot sont appliquées de manière atomique.

Ce code montre comment écrire les données :

void InsertData(google::cloud::spanner::Client client) {
  namespace spanner = ::google::cloud::spanner;
  auto insert_singers = spanner::InsertMutationBuilder(
                            "Singers", {"SingerId", "FirstName", "LastName"})
                            .EmplaceRow(1, "Marc", "Richards")
                            .EmplaceRow(2, "Catalina", "Smith")
                            .EmplaceRow(3, "Alice", "Trentor")
                            .EmplaceRow(4, "Lea", "Martin")
                            .EmplaceRow(5, "David", "Lomond")
                            .Build();

  auto insert_albums = spanner::InsertMutationBuilder(
                           "Albums", {"SingerId", "AlbumId", "AlbumTitle"})
                           .EmplaceRow(1, 1, "Total Junk")
                           .EmplaceRow(1, 2, "Go, Go, Go")
                           .EmplaceRow(2, 1, "Green")
                           .EmplaceRow(2, 2, "Forever Hold Your Peace")
                           .EmplaceRow(2, 3, "Terrified")
                           .Build();

  auto commit_result =
      client.Commit(spanner::Mutations{insert_singers, insert_albums});
  if (!commit_result) {
    throw std::runtime_error(commit_result.status().message());
  }
  std::cout << "Insert was successful [spanner_insert_data]\n";
}

C#

Vous pouvez insérer des données à l'aide de la méthode connection.CreateInsertCommand(), qui crée une commande SpannerCommand pour insérer des lignes dans une table. La méthode SpannerCommand.ExecuteNonQueryAsync() ajoute des lignes à la table.

Le code suivant décrit comment insérer des données :

public class Singer
{
    public int SingerId { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

public class Album
{
    public int SingerId { get; set; }
    public int AlbumId { get; set; }
    public string AlbumTitle { get; set; }
}
public static async Task InsertSampleDataAsync(
    string projectId, string instanceId, string databaseId)
{
    const int firstSingerId = 1;
    const int secondSingerId = 2;
    string connectionString =
    $"Data Source=projects/{projectId}/instances/{instanceId}"
    + $"/databases/{databaseId}";
    List<Singer> singers = new List<Singer>
    {
        new Singer { SingerId = firstSingerId, FirstName = "Marc",
            LastName = "Richards" },
        new Singer { SingerId = secondSingerId, FirstName = "Catalina",
            LastName = "Smith" },
        new Singer { SingerId = 3, FirstName = "Alice",
            LastName = "Trentor" },
        new Singer { SingerId = 4, FirstName = "Lea",
            LastName = "Martin" },
        new Singer { SingerId = 5, FirstName = "David",
            LastName = "Lomond" },
    };
    List<Album> albums = new List<Album>
    {
        new Album { SingerId = firstSingerId, AlbumId = 1,
            AlbumTitle = "Total Junk" },
        new Album { SingerId = firstSingerId, AlbumId = 2,
            AlbumTitle = "Go, Go, Go" },
        new Album { SingerId = secondSingerId, AlbumId = 1,
            AlbumTitle = "Green" },
        new Album { SingerId = secondSingerId, AlbumId = 2,
            AlbumTitle = "Forever Hold your Peace" },
        new Album { SingerId = secondSingerId, AlbumId = 3,
            AlbumTitle = "Terrified" },
    };
    // Create connection to Cloud Spanner.
    using (var connection = new SpannerConnection(connectionString))
    {
        await connection.OpenAsync();

        await connection.RunWithRetriableTransactionAsync(async transaction =>
        {
            // Insert rows into the Singers table.
            var cmd = connection.CreateInsertCommand("Singers",
                new SpannerParameterCollection
                {
                    { "SingerId", SpannerDbType.Int64 },
                    { "FirstName", SpannerDbType.String },
                    { "LastName", SpannerDbType.String }
                });
            cmd.Transaction = transaction;
            await Task.WhenAll(singers.Select(singer =>
            {
                cmd.Parameters["SingerId"].Value = singer.SingerId;
                cmd.Parameters["FirstName"].Value = singer.FirstName;
                cmd.Parameters["LastName"].Value = singer.LastName;
                return cmd.ExecuteNonQueryAsync();
            }));

            // Insert rows into the Albums table.
            cmd = connection.CreateInsertCommand("Albums",
                new SpannerParameterCollection
                {
                    { "SingerId", SpannerDbType.Int64 },
                    { "AlbumId", SpannerDbType.Int64 },
                    { "AlbumTitle", SpannerDbType.String }
                });
            cmd.Transaction = transaction;
            await Task.WhenAll(albums.Select(album =>
            {
                cmd.Parameters["SingerId"].Value = album.SingerId;
                cmd.Parameters["AlbumId"].Value = album.AlbumId;
                cmd.Parameters["AlbumTitle"].Value = album.AlbumTitle;
                return cmd.ExecuteNonQueryAsync();
            }));
        });
        Console.WriteLine("Inserted data.");
    }
}

Go

Vous pouvez écrire des données à l'aide d'un objet Mutation. L'objet Mutation est un conteneur destiné aux opérations de mutation. Une Mutation représente une séquence d'opérations (insertions, mises à jour, suppressions, etc.) pouvant être appliquées de manière atomique à différentes lignes et tables d'une base de données Cloud Spanner.

Utilisez Mutation.InsertOrUpdate() pour créer une mutation INSERT_OR_UPDATE, qui ajoute une ligne ou met à jour les valeurs de colonne si la ligne existe déjà. Autrement, vous pouvez aussi utiliser la méthode Mutation.Insert() pour créer une mutation INSERT, qui ajoute une ligne.

La méthode Client.Apply() applique les mutations de manière atomique à une base de données.

Ce code montre comment écrire les données :


import (
	"context"
	"io"

	"cloud.google.com/go/spanner"
)

func write(w io.Writer, db string) error {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, db)
	if err != nil {
		return err
	}
	defer client.Close()

	singerColumns := []string{"SingerId", "FirstName", "LastName"}
	albumColumns := []string{"SingerId", "AlbumId", "AlbumTitle"}
	m := []*spanner.Mutation{
		spanner.InsertOrUpdate("Singers", singerColumns, []interface{}{1, "Marc", "Richards"}),
		spanner.InsertOrUpdate("Singers", singerColumns, []interface{}{2, "Catalina", "Smith"}),
		spanner.InsertOrUpdate("Singers", singerColumns, []interface{}{3, "Alice", "Trentor"}),
		spanner.InsertOrUpdate("Singers", singerColumns, []interface{}{4, "Lea", "Martin"}),
		spanner.InsertOrUpdate("Singers", singerColumns, []interface{}{5, "David", "Lomond"}),
		spanner.InsertOrUpdate("Albums", albumColumns, []interface{}{1, 1, "Total Junk"}),
		spanner.InsertOrUpdate("Albums", albumColumns, []interface{}{1, 2, "Go, Go, Go"}),
		spanner.InsertOrUpdate("Albums", albumColumns, []interface{}{2, 1, "Green"}),
		spanner.InsertOrUpdate("Albums", albumColumns, []interface{}{2, 2, "Forever Hold Your Peace"}),
		spanner.InsertOrUpdate("Albums", albumColumns, []interface{}{2, 3, "Terrified"}),
	}
	_, err = client.Apply(ctx, m)
	return err
}

Java

Vous pouvez écrire des données à l'aide d'un objet Mutation. L'objet Mutation est un conteneur destiné aux opérations de mutation. Un objet Mutation représente une séquence d'opérations (insertions, mises à jour, suppressions, etc.) que Cloud Spanner applique de manière atomique à différentes lignes et tables d'une base de données Cloud Spanner.

La méthode newInsertBuilder() de la classe Mutation crée une mutation INSERT, qui insère une nouvelle ligne dans une table. Si la ligne existe déjà, l'écriture échoue. Autrement, vous pouvez aussi utiliser la méthode newInsertOrUpdateBuilder pour créer une mutation INSERT_OR_UPDATE, qui ajoute une ligne ou met à jour les valeurs de colonne si la ligne existe déjà.

La méthode write() de la classe DatabaseClient écrit les mutations. Toutes les mutations d'un même lot sont appliquées de manière atomique

Ce code montre comment écrire les données :

static final List<Singer> SINGERS =
    Arrays.asList(
        new Singer(1, "Marc", "Richards"),
        new Singer(2, "Catalina", "Smith"),
        new Singer(3, "Alice", "Trentor"),
        new Singer(4, "Lea", "Martin"),
        new Singer(5, "David", "Lomond"));

static final List<Album> ALBUMS =
    Arrays.asList(
        new Album(1, 1, "Total Junk"),
        new Album(1, 2, "Go, Go, Go"),
        new Album(2, 1, "Green"),
        new Album(2, 2, "Forever Hold Your Peace"),
        new Album(2, 3, "Terrified"));
static void writeExampleData(DatabaseClient dbClient) {
  List<Mutation> mutations = new ArrayList<>();
  for (Singer singer : SINGERS) {
    mutations.add(
        Mutation.newInsertBuilder("Singers")
            .set("SingerId")
            .to(singer.singerId)
            .set("FirstName")
            .to(singer.firstName)
            .set("LastName")
            .to(singer.lastName)
            .build());
  }
  for (Album album : ALBUMS) {
    mutations.add(
        Mutation.newInsertBuilder("Albums")
            .set("SingerId")
            .to(album.singerId)
            .set("AlbumId")
            .to(album.albumId)
            .set("AlbumTitle")
            .to(album.albumTitle)
            .build());
  }
  dbClient.write(mutations);
}

Node.js

Vous pouvez écrire des données à l'aide d'un objet Table. La méthode Table.insert() ajoute des lignes à la table. Toutes les insertions d'un même lot sont appliquées de manière atomique.

Ce code montre comment écrire les données :

// 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 objects
const singersTable = database.table('Singers');
const albumsTable = database.table('Albums');

// Inserts rows into the Singers table
// Note: Cloud Spanner interprets Node.js numbers as FLOAT64s, so
// they must be converted to strings before being inserted as INT64s
try {
  await singersTable.insert([
    {SingerId: '1', FirstName: 'Marc', LastName: 'Richards'},
    {SingerId: '2', FirstName: 'Catalina', LastName: 'Smith'},
    {SingerId: '3', FirstName: 'Alice', LastName: 'Trentor'},
    {SingerId: '4', FirstName: 'Lea', LastName: 'Martin'},
    {SingerId: '5', FirstName: 'David', LastName: 'Lomond'},
  ]);

  await albumsTable.insert([
    {SingerId: '1', AlbumId: '1', AlbumTitle: 'Total Junk'},
    {SingerId: '1', AlbumId: '2', AlbumTitle: 'Go, Go, Go'},
    {SingerId: '2', AlbumId: '1', AlbumTitle: 'Green'},
    {SingerId: '2', AlbumId: '2', AlbumTitle: 'Forever Hold your Peace'},
    {SingerId: '2', AlbumId: '3', AlbumTitle: 'Terrified'},
  ]);

  console.log('Inserted data.');
} catch (err) {
  console.error('ERROR:', err);
} finally {
  await database.close();
}

PHP

Vous pouvez écrire des données à l'aide de la méthode Database::insertBatch. insertBatch ajoute des lignes à une table. Toutes les insertions d'un même lot sont appliquées de manière atomique.

Ce code montre comment écrire les données :

use Google\Cloud\Spanner\SpannerClient;

/**
 * Inserts sample data into the given database.
 *
 * 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 $databaseId The Spanner database ID.
 */
function insert_data($instanceId, $databaseId)
{
    $spanner = new SpannerClient();
    $instance = $spanner->instance($instanceId);
    $database = $instance->database($databaseId);

    $operation = $database->transaction(['singleUse' => true])
        ->insertBatch('Singers', [
            ['SingerId' => 1, 'FirstName' => 'Marc', 'LastName' => 'Richards'],
            ['SingerId' => 2, 'FirstName' => 'Catalina', 'LastName' => 'Smith'],
            ['SingerId' => 3, 'FirstName' => 'Alice', 'LastName' => 'Trentor'],
            ['SingerId' => 4, 'FirstName' => 'Lea', 'LastName' => 'Martin'],
            ['SingerId' => 5, 'FirstName' => 'David', 'LastName' => 'Lomond'],
        ])
        ->insertBatch('Albums', [
            ['SingerId' => 1, 'AlbumId' => 1, 'AlbumTitle' => 'Total Junk'],
            ['SingerId' => 1, 'AlbumId' => 2, 'AlbumTitle' => 'Go, Go, Go'],
            ['SingerId' => 2, 'AlbumId' => 1, 'AlbumTitle' => 'Green'],
            ['SingerId' => 2, 'AlbumId' => 2, 'AlbumTitle' => 'Forever Hold Your Peace'],
            ['SingerId' => 2, 'AlbumId' => 3, 'AlbumTitle' => 'Terrified']
        ])
        ->commit();

    print('Inserted data.' . PHP_EOL);
}

Python

Vous pouvez écrire des données à l'aide d'un objet Batch. L'objet Batch est un conteneur destiné aux opérations de mutation. Une mutation représente une séquence d'opérations (insertions, mises à jour, suppressions, etc.) pouvant être appliquées de manière atomique à différentes lignes et tables d'une base de données Cloud Spanner.

La méthode insert() de la classe Batch permet d'ajouter une ou plusieurs mutations d'insertion au lot. Toutes les mutations d'un même lot sont appliquées de manière atomique.

Ce code montre comment écrire les données :

def insert_data(instance_id, database_id):
    """Inserts sample data into the given database.

    The database and table must already exist and can be created using
    `create_database`.
    """
    spanner_client = spanner.Client()
    instance = spanner_client.instance(instance_id)
    database = instance.database(database_id)

    with database.batch() as batch:
        batch.insert(
            table="Singers",
            columns=("SingerId", "FirstName", "LastName"),
            values=[
                (1, u"Marc", u"Richards"),
                (2, u"Catalina", u"Smith"),
                (3, u"Alice", u"Trentor"),
                (4, u"Lea", u"Martin"),
                (5, u"David", u"Lomond"),
            ],
        )

        batch.insert(
            table="Albums",
            columns=("SingerId", "AlbumId", "AlbumTitle"),
            values=[
                (1, 1, u"Total Junk"),
                (1, 2, u"Go, Go, Go"),
                (2, 1, u"Green"),
                (2, 2, u"Forever Hold Your Peace"),
                (2, 3, u"Terrified"),
            ],
        )

    print("Inserted data.")

Ruby

Vous pouvez écrire des données à l'aide d'un objet Client. La méthode Client#commit permet la création et le commit d'une transaction pour les écritures, qui s'exécutent de manière atomique à un même instant logique dans les colonnes, les lignes et les tables d'une base de données.

Ce code montre comment écrire les données :

# 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

client.commit do |c|
  c.insert "Singers", [
    { SingerId: 1, FirstName: "Marc",     LastName: "Richards" },
    { SingerId: 2, FirstName: "Catalina", LastName: "Smith"    },
    { SingerId: 3, FirstName: "Alice",    LastName: "Trentor"  },
    { SingerId: 4, FirstName: "Lea",      LastName: "Martin"   },
    { SingerId: 5, FirstName: "David",    LastName: "Lomond"   }
  ]
  c.insert "Albums", [
    { SingerId: 1, AlbumId: 1, AlbumTitle: "Total Junk"              },
    { SingerId: 1, AlbumId: 2, AlbumTitle: "Go, Go, Go"              },
    { SingerId: 2, AlbumId: 1, AlbumTitle: "Green"                   },
    { SingerId: 2, AlbumId: 2, AlbumTitle: "Forever Hold Your Peace" },
    { SingerId: 2, AlbumId: 3, AlbumTitle: "Terrified"               }
  ]
end

puts "Inserted data"

Mettre à jour les lignes dans une table

Supposons que les ventes enregistrées pour Albums(1, 1) soient inférieures aux prévisions. Pour cette raison, vous souhaitez transférer 200 000 $ du budget marketing de Albums(2, 2) vers Albums(1, 1), mais uniquement si la somme est disponible dans le budget de Albums(2, 2).

Étant donné que vous avez besoin de lire les données des tables pour déterminer si vous devez écrire de nouvelles valeurs, il vous faudra utiliser une transaction en lecture/écriture pour effectuer des lectures et des écritures de façon atomique.

C++

Utilisez la fonction Transaction() pour exécuter une transaction pour un client.

Le code permettant d'exécuter la transaction est présenté ci-dessous :

void ReadWriteTransaction(google::cloud::spanner::Client client) {
  namespace spanner = ::google::cloud::spanner;
  using ::google::cloud::StatusOr;

  // A helper to read a single album MarketingBudget.
  auto get_current_budget =
      [](spanner::Client client, spanner::Transaction txn,
         std::int64_t singer_id,
         std::int64_t album_id) -> StatusOr<std::int64_t> {
    auto key = spanner::KeySet().AddKey(spanner::MakeKey(singer_id, album_id));
    auto rows = client.Read(std::move(txn), "Albums", std::move(key),
                            {"MarketingBudget"});
    using RowType = std::tuple<std::int64_t>;
    auto row = spanner::GetSingularRow(spanner::StreamOf<RowType>(rows));
    if (!row) return std::move(row).status();
    return std::get<0>(*std::move(row));
  };

  auto commit = client.Commit(
      [&client, &get_current_budget](
          spanner::Transaction const& txn) -> StatusOr<spanner::Mutations> {
        auto b1 = get_current_budget(client, txn, 1, 1);
        if (!b1) return std::move(b1).status();
        auto b2 = get_current_budget(client, txn, 2, 2);
        if (!b2) return std::move(b2).status();
        std::int64_t transfer_amount = 200000;

        return spanner::Mutations{
            spanner::UpdateMutationBuilder(
                "Albums", {"SingerId", "AlbumId", "MarketingBudget"})
                .EmplaceRow(1, 1, *b1 + transfer_amount)
                .EmplaceRow(2, 2, *b2 - transfer_amount)
                .Build()};
      });

  if (!commit) throw std::runtime_error(commit.status().message());
  std::cout << "Transfer was successful [spanner_read_write_transaction]\n";
}

C#

Pour .NET Standard 2.0 (ou .NET 4.5) et versions ultérieures, vous pouvez utiliser la méthode TransactionScope() du framework .NET pour exécuter une transaction. Pour toutes les versions compatibles de .NET, vous pouvez créer une transaction en définissant le résultat de SpannerConnection.BeginTransactionAsync en tant que propriété Transaction de SpannerCommand.

Voici deux méthodes permettant d'exécuter la transaction :

.NET Standard 2.0

public static async Task ReadWriteWithTransactionAsync(
    string projectId,
    string instanceId,
    string databaseId)
{
    // This sample transfers 200,000 from the MarketingBudget
    // field of the second Album to the first Album. Make sure to run
    // the addColumn and writeDataToNewColumn samples first,
    // in that order.

    string connectionString =
    $"Data Source=projects/{projectId}/instances/{instanceId}"
    + $"/databases/{databaseId}";

    using (TransactionScope scope = new TransactionScope(
        TransactionScopeAsyncFlowOption.Enabled))
    {
        decimal transferAmount = 200000;
        decimal secondBudget = 0;
        decimal firstBudget = 0;

        // Create connection to Cloud Spanner.
        using (var connection =
            new SpannerConnection(connectionString))
        {
            // Create statement to select the second album's data.
            var cmdLookup = connection.CreateSelectCommand(
            "SELECT * FROM Albums WHERE SingerId = 2 AND AlbumId = 2");
            // Excecute the select query.
            using (var reader = await cmdLookup.ExecuteReaderAsync())
            {
                while (await reader.ReadAsync())
                {
                    // Read the second album's budget.
                    secondBudget =
                      reader.GetFieldValue<decimal>("MarketingBudget");
                    // Confirm second Album's budget is sufficient and
                    // if not raise an exception. Raising an exception
                    // will automatically roll back the transaction.
                    if (secondBudget < transferAmount)
                    {
                        throw new Exception("The second album's "
                            + $"budget {secondBudget} "
                            + "is less than the "
                            + "amount to transfer.");
                    }
                }
            }
            // Read the first album's budget.
            cmdLookup = connection.CreateSelectCommand(
            "SELECT * FROM Albums WHERE SingerId = 1 and AlbumId = 1");
            using (var reader = await cmdLookup.ExecuteReaderAsync())
            {
                while (await reader.ReadAsync())
                {
                    firstBudget =
                      reader.GetFieldValue<decimal>("MarketingBudget");
                }
            }

            // Specify update command parameters.
            var cmd = connection.CreateUpdateCommand("Albums",
                new SpannerParameterCollection {
                {"SingerId", SpannerDbType.Int64},
                {"AlbumId", SpannerDbType.Int64},
                {"MarketingBudget", SpannerDbType.Int64},
            });
            // Update second album to remove the transfer amount.
            secondBudget -= transferAmount;
            cmd.Parameters["SingerId"].Value = 2;
            cmd.Parameters["AlbumId"].Value = 2;
            cmd.Parameters["MarketingBudget"].Value = secondBudget;
            await cmd.ExecuteNonQueryAsync();
            // Update first album to add the transfer amount.
            firstBudget += transferAmount;
            cmd.Parameters["SingerId"].Value = 1;
            cmd.Parameters["AlbumId"].Value = 1;
            cmd.Parameters["MarketingBudget"].Value = firstBudget;
            await cmd.ExecuteNonQueryAsync();
            scope.Complete();
            Console.WriteLine("Transaction complete.");
        }
    }
}

.NET Standard 1.5

public static async Task ReadWriteWithTransactionCoreAsync(
    string projectId,
    string instanceId,
    string databaseId)
{
    // This sample transfers 200,000 from the MarketingBudget
    // field of the second Album to the first Album. Make sure to run
    // the addColumn and writeDataToNewColumn samples first,
    // in that order.
    string connectionString =
        $"Data Source=projects/{projectId}/instances/{instanceId}"
        + $"/databases/{databaseId}";

    decimal transferAmount = 200000;
    decimal secondBudget = 0;
    decimal firstBudget = 0;

    Console.WriteLine(".NetCore API sample.");

    // Create connection to Cloud Spanner.
    using (var connection =
        new SpannerConnection(connectionString))
    {
        await connection.OpenAsync();

        // Create a readwrite transaction that we'll assign
        // to each SpannerCommand.
        using (var transaction =
                await connection.BeginTransactionAsync())
        {
            // Create statement to select the second album's data.
            var cmdLookup = connection.CreateSelectCommand(
             "SELECT * FROM Albums WHERE SingerId = 2 AND AlbumId = 2");
            cmdLookup.Transaction = transaction;
            // Excecute the select query.
            using (var reader = await cmdLookup.ExecuteReaderAsync())
            {
                while (await reader.ReadAsync())
                {
                    // Read the second album's budget.
                    secondBudget =
                       reader.GetFieldValue<decimal>("MarketingBudget");
                    // Confirm second Album's budget is sufficient and
                    // if not raise an exception. Raising an exception
                    // will automatically roll back the transaction.
                    if (secondBudget < transferAmount)
                    {
                        throw new Exception("The second album's "
                                + $"budget {secondBudget} "
                                + "contains less than the "
                                + "amount to transfer.");
                    }
                }
            }
            // Read the first album's budget.
            cmdLookup = connection.CreateSelectCommand(
             "SELECT * FROM Albums WHERE SingerId = 1 and AlbumId = 1");
            cmdLookup.Transaction = transaction;
            using (var reader = await cmdLookup.ExecuteReaderAsync())
            {
                while (await reader.ReadAsync())
                {
                    firstBudget =
                      reader.GetFieldValue<decimal>("MarketingBudget");
                }
            }

            // Specify update command parameters.
            var cmd = connection.CreateUpdateCommand("Albums",
                new SpannerParameterCollection
                {
                    {"SingerId", SpannerDbType.Int64},
                    {"AlbumId", SpannerDbType.Int64},
                    {"MarketingBudget", SpannerDbType.Int64},
                });
            cmd.Transaction = transaction;
            // Update second album to remove the transfer amount.
            secondBudget -= transferAmount;
            cmd.Parameters["SingerId"].Value = 2;
            cmd.Parameters["AlbumId"].Value = 2;
            cmd.Parameters["MarketingBudget"].Value = secondBudget;
            await cmd.ExecuteNonQueryAsync();
            // Update first album to add the transfer amount.
            firstBudget += transferAmount;
            cmd.Parameters["SingerId"].Value = 1;
            cmd.Parameters["AlbumId"].Value = 1;
            cmd.Parameters["MarketingBudget"].Value = firstBudget;
            await cmd.ExecuteNonQueryAsync();

            await transaction.CommitAsync();
        }
        Console.WriteLine("Transaction complete.");
    }
}

Go

Utilisez le type ReadWriteTransaction pour exécuter un ensemble de tâches dans le contexte d'une transaction en lecture/écriture. Client.ReadWriteTransaction() renvoie un objet ReadWriteTransaction.

L'exemple utilise ReadWriteTransaction.ReadRow() pour récupérer une ligne de données.

Il inclut également ReadWriteTransaction.BufferWrite(), qui ajoute une liste de mutations à l'ensemble des mises à jour qui seront appliquées lors du commit de la transaction.

L'exemple fait également appel au type Key, qui représente une clé de ligne dans une table ou un index Cloud Spanner.


import (
	"context"
	"fmt"
	"io"

	"cloud.google.com/go/spanner"
)

func writeWithTransaction(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 {
		getBudget := func(key spanner.Key) (int64, error) {
			row, err := txn.ReadRow(ctx, "Albums", key, []string{"MarketingBudget"})
			if err != nil {
				return 0, err
			}
			var budget int64
			if err := row.Column(0, &budget); err != nil {
				return 0, err
			}
			return budget, nil
		}
		album2Budget, err := getBudget(spanner.Key{2, 2})
		if err != nil {
			return err
		}
		const transferAmt = 200000
		if album2Budget >= transferAmt {
			album1Budget, err := getBudget(spanner.Key{1, 1})
			if err != nil {
				return err
			}
			album1Budget += transferAmt
			album2Budget -= transferAmt
			cols := []string{"SingerId", "AlbumId", "MarketingBudget"}
			txn.BufferWrite([]*spanner.Mutation{
				spanner.Update("Albums", cols, []interface{}{1, 1, album1Budget}),
				spanner.Update("Albums", cols, []interface{}{2, 2, album2Budget}),
			})
			fmt.Fprintf(w, "Moved %d from Album2's MarketingBudget to Album1's.", transferAmt)
		}
		return nil
	})
	return err
}

Java

Utilisez l'interface TransactionRunner pour exécuter un ensemble de tâches dans le contexte d'une transaction en lecture/écriture. Cette interface contient la méthode run(), qui permet d'exécuter une transaction en lecture/écriture, avec plusieurs tentatives si nécessaire. La méthode readWriteTransaction de la classe DatabaseClient renvoie un objet TransactionRunner permettant d'exécuter une seule transaction logique.

La classe TransactionRunner.TransactionCallable inclut une méthode run() permettant d'effectuer une seule tentative de transaction. run() utilise un objet TransactionContext, qui correspond au contexte de la transaction.

L'exemple utilise la classe Struct, qui s'avère pratique pour stocker les résultats des appels readRow(). Il fait également appel à la classe Key, qui représente une clé de ligne dans une table ou un index Cloud Spanner.

Le code permettant d'exécuter la transaction est présenté ci-dessous :

static void writeWithTransaction(DatabaseClient dbClient) {
  dbClient
      .readWriteTransaction()
      .run(transaction -> {
        // Transfer marketing budget from one album to another. We do it in a transaction to
        // ensure that the transfer is atomic.
        Struct row =
            transaction.readRow("Albums", Key.of(2, 2), Arrays.asList("MarketingBudget"));
        long album2Budget = row.getLong(0);
        // Transaction will only be committed if this condition still holds at the time of
        // commit. Otherwise it will be aborted and the callable will be rerun by the
        // client library.
        long transfer = 200000;
        if (album2Budget >= transfer) {
          long album1Budget =
              transaction
                  .readRow("Albums", Key.of(1, 1), Arrays.asList("MarketingBudget"))
                  .getLong(0);
          album1Budget += transfer;
          album2Budget -= transfer;
          transaction.buffer(
              Mutation.newUpdateBuilder("Albums")
                  .set("SingerId")
                  .to(1)
                  .set("AlbumId")
                  .to(1)
                  .set("MarketingBudget")
                  .to(album1Budget)
                  .build());
          transaction.buffer(
              Mutation.newUpdateBuilder("Albums")
                  .set("SingerId")
                  .to(2)
                  .set("AlbumId")
                  .to(2)
                  .set("MarketingBudget")
                  .to(album2Budget)
                  .build());
        }
        return null;
      });
}

Node.js

Utilisez Database.runTransaction() pour exécuter une transaction.

Le code permettant d'exécuter la transaction est présenté ci-dessous :

// This sample transfers 200,000 from the MarketingBudget field
// of the second Album to the first Album, as long as the second
// Album has enough money in its budget. Make sure to run the
// addColumn and updateData samples first (in that order).

// 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 transferAmount = 200000;

database.runTransaction(async (err, transaction) => {
  if (err) {
    console.error(err);
    return;
  }
  let firstBudget, secondBudget;
  const queryOne = {
    columns: ['MarketingBudget'],
    keys: [[2, 2]], // SingerId: 2, AlbumId: 2
  };

  const queryTwo = {
    columns: ['MarketingBudget'],
    keys: [[1, 1]], // SingerId: 1, AlbumId: 1
  };

  Promise.all([
    // Reads the second album's budget
    transaction.read('Albums', queryOne).then(results => {
      // Gets second album's budget
      const rows = results[0].map(row => row.toJSON());
      secondBudget = rows[0].MarketingBudget;
      console.log(`The second album's marketing budget: ${secondBudget}`);

      // Makes sure the second album's budget is large enough
      if (secondBudget < transferAmount) {
        throw new Error(
          `The second album's budget (${secondBudget}) is less than the transfer amount (${transferAmount}).`
        );
      }
    }),

    // Reads the first album's budget
    transaction.read('Albums', queryTwo).then(results => {
      // Gets first album's budget
      const rows = results[0].map(row => row.toJSON());
      firstBudget = rows[0].MarketingBudget;
      console.log(`The first album's marketing budget: ${firstBudget}`);
    }),
  ])
    .then(() => {
      console.log(firstBudget, secondBudget);
      // Transfers the budgets between the albums
      firstBudget += transferAmount;
      secondBudget -= transferAmount;

      console.log(firstBudget, secondBudget);

      // Updates the database
      // Note: Cloud Spanner interprets Node.js numbers as FLOAT64s, so they
      // must be converted (back) to strings before being inserted as INT64s.
      transaction.update('Albums', [
        {
          SingerId: '1',
          AlbumId: '1',
          MarketingBudget: firstBudget.toString(),
        },
        {
          SingerId: '2',
          AlbumId: '2',
          MarketingBudget: secondBudget.toString(),
        },
      ]);
    })
    .then(() => {
      // Commits the transaction and send the changes to the database
      return transaction.commit();
    })
    .then(() => {
      console.log(
        `Successfully executed read-write transaction to transfer ${transferAmount} from Album 2 to Album 1.`
      );
    })
    .catch(err => {
      console.error('ERROR:', err);
    })
    .then(() => {
      transaction.end();
      // Closes the database when finished
      return database.close();
    });
});

PHP

Utilisez Database::runTransaction pour exécuter une transaction.

Le code permettant d'exécuter la transaction est présenté ci-dessous :

use Google\Cloud\Spanner\SpannerClient;
use Google\Cloud\Spanner\Transaction;
use UnexpectedValueException;

/**
 * Performs a read-write transaction to update two sample records in the
 * database.
 *
 * This will transfer 200,000 from the `MarketingBudget` field for the second
 * Album to the first Album. If the `MarketingBudget` for the second Album is
 * too low, it will raise an exception.
 *
 * Before running this sample, you will need to run the `update_data` sample
 * to populate the fields.
 * Example:
 * ```
 * read_write_transaction($instanceId, $databaseId);
 * ```
 *
 * @param string $instanceId The Spanner instance ID.
 * @param string $databaseId The Spanner database ID.
 */
function read_write_transaction($instanceId, $databaseId)
{
    $spanner = new SpannerClient();
    $instance = $spanner->instance($instanceId);
    $database = $instance->database($databaseId);

    $database->runTransaction(function (Transaction $t) use ($spanner) {
        $transferAmount = 200000;

        // Read the second album's budget.
        $secondAlbumKey = [2, 2];
        $secondAlbumKeySet = $spanner->keySet(['keys' => [$secondAlbumKey]]);
        $secondAlbumResult = $t->read(
            'Albums',
            $secondAlbumKeySet,
            ['MarketingBudget'],
            ['limit' => 1]
        );

        $firstRow = $secondAlbumResult->rows()->current();
        $secondAlbumBudget = $firstRow['MarketingBudget'];
        if ($secondAlbumBudget < $transferAmount) {
            // Throwing an exception will automatically roll back the transaction.
            throw new UnexpectedValueException(
                'The second album\'s budget is lower than the transfer amount: ' . $transferAmount
            );
        }

        $firstAlbumKey = [1, 1];
        $firstAlbumKeySet = $spanner->keySet(['keys' => [$firstAlbumKey]]);
        $firstAlbumResult = $t->read(
            'Albums',
            $firstAlbumKeySet,
            ['MarketingBudget'],
            ['limit' => 1]
        );

        // Read the first album's budget.
        $firstRow = $firstAlbumResult->rows()->current();
        $firstAlbumBudget = $firstRow['MarketingBudget'];

        // Update the budgets.
        $secondAlbumBudget -= $transferAmount;
        $firstAlbumBudget += $transferAmount;
        printf('Setting first album\'s budget to %s and the second album\'s ' .
            'budget to %s.' . PHP_EOL, $firstAlbumBudget, $secondAlbumBudget);

        // Update the rows.
        $t->updateBatch('Albums', [
            ['SingerId' => 1, 'AlbumId' => 1, 'MarketingBudget' => $firstAlbumBudget],
            ['SingerId' => 2, 'AlbumId' => 2, 'MarketingBudget' => $secondAlbumBudget],
        ]);

        // Commit the transaction!
        $t->commit();

        print('Transaction complete.' . PHP_EOL);
    });
}

Python

Utilisez la méthode run_in_transaction() de la classe Database pour exécuter une transaction.

Le code permettant d'exécuter la transaction est présenté ci-dessous :

def read_write_transaction(instance_id, database_id):
    """Performs a read-write transaction to update two sample records in the
    database.

    This will transfer 200,000 from the `MarketingBudget` field for the second
    Album to the first Album. If the `MarketingBudget` is too low, it will
    raise an exception.

    Before running this sample, you will need to run the `update_data` sample
    to populate the fields.
    """
    spanner_client = spanner.Client()
    instance = spanner_client.instance(instance_id)
    database = instance.database(database_id)

    def update_albums(transaction):
        # Read the second album budget.
        second_album_keyset = spanner.KeySet(keys=[(2, 2)])
        second_album_result = transaction.read(
            table="Albums",
            columns=("MarketingBudget",),
            keyset=second_album_keyset,
            limit=1,
        )
        second_album_row = list(second_album_result)[0]
        second_album_budget = second_album_row[0]

        transfer_amount = 200000

        if second_album_budget < transfer_amount:
            # Raising an exception will automatically roll back the
            # transaction.
            raise ValueError("The second album doesn't have enough funds to transfer")

        # Read the first album's budget.
        first_album_keyset = spanner.KeySet(keys=[(1, 1)])
        first_album_result = transaction.read(
            table="Albums",
            columns=("MarketingBudget",),
            keyset=first_album_keyset,
            limit=1,
        )
        first_album_row = list(first_album_result)[0]
        first_album_budget = first_album_row[0]

        # Update the budgets.
        second_album_budget -= transfer_amount
        first_album_budget += transfer_amount
        print(
            "Setting first album's budget to {} and the second album's "
            "budget to {}.".format(first_album_budget, second_album_budget)
        )

        # Update the rows.
        transaction.update(
            table="Albums",
            columns=("SingerId", "AlbumId", "MarketingBudget"),
            values=[(1, 1, first_album_budget), (2, 2, second_album_budget)],
        )

    database.run_in_transaction(update_albums)

    print("Transaction complete.")

Ruby

Utilisez la méthode transaction de la classe Client pour exécuter une transaction.

Le code permettant d'exécuter la transaction est présenté ci-dessous :

# 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
transfer_amount = 200_000

client.transaction do |transaction|
  first_album  = transaction.read("Albums", [:MarketingBudget], keys: [[1, 1]]).rows.first
  second_album = transaction.read("Albums", [:MarketingBudget], keys: [[2, 2]]).rows.first

  raise "The second album does not have enough funds to transfer" if second_album[:MarketingBudget] < transfer_amount

  new_first_album_budget  = first_album[:MarketingBudget] + transfer_amount
  new_second_album_budget = second_album[:MarketingBudget] - transfer_amount

  transaction.update "Albums", [
    { SingerId: 1, AlbumId: 1, MarketingBudget: new_first_album_budget  },
    { SingerId: 2, AlbumId: 2, MarketingBudget: new_second_album_budget }
  ]
end

puts "Transaction complete"

Supprimer des lignes dans une table

Chaque bibliothèque client offre plusieurs moyens de supprimer des lignes :

  • Supprimer toutes les lignes d'une table
  • Supprimer une seule ligne en spécifiant les valeurs de colonne clé pour la ligne
  • Supprimer un groupe de lignes en créant une plage de clés
  • Supprimer des lignes dans une table entrelacée en supprimant les lignes parentes, si cette table inclut ON DELETE CASCADE dans sa définition de schéma

C++

Supprimez des lignes à l'aide de la fonction DeleteMutationBuilder() pour un client.

Ce code montre comment supprimer les données :

void DeleteData(google::cloud::spanner::Client client) {
  namespace spanner = ::google::cloud::spanner;

  // Delete the albums with key (2,1) and (2,3).
  auto delete_albums = spanner::DeleteMutationBuilder(
                           "Albums", spanner::KeySet()
                                         .AddKey(spanner::MakeKey(2, 1))
                                         .AddKey(spanner::MakeKey(2, 3)))
                           .Build();

  // Delete some singers using the keys in the range [3, 5]
  auto delete_singers_range =
      spanner::DeleteMutationBuilder(
          "Singers", spanner::KeySet().AddRange(spanner::MakeKeyBoundClosed(3),
                                                spanner::MakeKeyBoundOpen(5)))
          .Build();

  // 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::runtime_error(commit_result.status().message());
  }
  std::cout << "Delete was successful [spanner_delete_data]\n";
}

C#

Supprimez des lignes à l'aide de la méthode connection.CreateDeleteCommand(), qui crée une commande SpannerCommand pour supprimer des lignes. La méthode SpannerCommand.ExecuteNonQueryAsync() supprime les lignes de la table.

Cet exemple supprime les lignes de la table Singers de manière individuelle. Les lignes de la table Albums sont supprimées, car cette table Albums est entrelacée dans la table Singers et définie avec ON DELETE CASCADE.

public static async Task DeleteIndividualRowsAsync(
    string projectId, string instanceId, string databaseId)
{
    const int singerId = 2;
    string connectionString =
        $"Data Source=projects/{projectId}/instances/{instanceId}"
        + $"/databases/{databaseId}";
    List<Album> albums = new List<Album>
    {
        new Album { SingerId = singerId, AlbumId = 1, AlbumTitle = "Green" },
        new Album { SingerId = singerId, AlbumId = 3, AlbumTitle = "Terrified" },
    };
    // Create connection to Cloud Spanner.
    using (var connection = new SpannerConnection(connectionString))
    {
        await connection.OpenAsync();

        // Delete individual rows from the UpcomingAlbums table.
        await Task.WhenAll(albums.Select(album =>
        {
            var cmd = connection.CreateDeleteCommand(
                "UpcomingAlbums",
                new SpannerParameterCollection
                {
                    { "SingerId", SpannerDbType.Int64, album.SingerId },
                    { "AlbumId", SpannerDbType.Int64, album.AlbumId }
                }
            );
            return cmd.ExecuteNonQueryAsync();
        }));

        Console.WriteLine("Deleted individual rows in UpcomingAlbums.");
    }
}

public static async Task DeleteRangeOfRowsAsync(
    string projectId, string instanceId, string databaseId)
{
    string connectionString =
        $"Data Source=projects/{projectId}/instances/{instanceId}"
        + $"/databases/{databaseId}";
    // Create connection to Cloud Spanner.
    using (var connection = new SpannerConnection(connectionString))
    {
        await connection.OpenAsync();

        // Delete a range of rows from the UpcomingSingers table where the column key is >=3 and <5.
        var cmd = connection.CreateDmlCommand(
           "DELETE FROM UpcomingSingers WHERE SingerId >= 3 AND SingerId < 5");
        int rowCount = await cmd.ExecuteNonQueryAsync();
        Console.WriteLine($"{rowCount} row(s) deleted from UpcomingSingers.");
    }
}

public static async Task DeleteAllRowsAsync(
    string projectId, string instanceId, string databaseId)
{
    string connectionString =
        $"Data Source=projects/{projectId}/instances/{instanceId}"
        + $"/databases/{databaseId}";
    // Create connection to Cloud Spanner.
    using (var connection = new SpannerConnection(connectionString))
    {
        await connection.OpenAsync();

        // Delete remaining UpcomingSingers rows, which will also delete the remaining
        // UpcomingAlbums rows since it was defined with ON DELETE CASCADE.
        var cmd = connection.CreateDmlCommand(
           "DELETE FROM UpcomingSingers WHERE true");
        int rowCount = await cmd.ExecuteNonQueryAsync();
        Console.WriteLine($"{rowCount} row(s) deleted from UpcomingSingers.");
    }
}

Go

Supprimez des lignes à l'aide d'un objet Mutation. Utilisez la méthode Mutation.Delete() pour créer une mutation DELETE, qui supprime une ligne. La méthode Client.Apply() applique des mutations de manière atomique à la base de données.

Cet exemple supprime les lignes de la table Albums de manière individuelle, puis toutes les lignes de la table Singers à l'aide d'un objet KeyRange.


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{
		// Delete individual rows.
		spanner.Delete("Albums", spanner.Key{2, 1}),
		spanner.Delete("Albums", spanner.Key{2, 3}),
		// 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}),
		// Delete remaining Singers rows, which will also delete the remaining
		// Albums rows because Albums was defined with ON DELETE CASCADE.
		spanner.Delete("Singers", spanner.AllKeys()),
	}
	_, err = client.Apply(ctx, m)
	return err
}

Java

Supprimez des lignes à l'aide de la méthode Mutation.delete().

Cet exemple utilise la méthode KeySet.all() pour supprimer toutes les lignes de la table Albums. Après la suppression des lignes de la table Albums, l'exemple supprime les lignes de la table Singers de manière individuelle à l'aide des clés créées avec la méthode KeySet.singleKey().

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

Supprimez des lignes à l'aide de la méthode table.deleteRows().

Cet exemple utilise la méthode table.deleteRows() pour supprimer toutes les lignes de la table Singers. Les lignes de la table Albums sont supprimées, car cette table Albums est entrelacée dans la table Singers et définie avec ON DELETE CASCADE.

// 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

Supprimez des lignes à l'aide de la méthode Database::delete() method. La page traitant de la méthode Database::delete() inclut un exemple.

Python

Supprimez des lignes à l'aide de la méthode Batch.delete().

Cet exemple supprime toutes les lignes des tables Albums et Singers de manière individuelle à l'aide d'un objet KeySet.

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

Supprimez des lignes à l'aide de la méthode Client#delete. La page traitant de Client#delete inclut un exemple.

# 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"