Requête avec le paramètre STRING

Interroger les données à l'aide d'un paramètre STRING.

Exemple de code

C++

Pour savoir comment installer et utiliser la bibliothèque cliente pour Spanner, consultez la page Bibliothèques clientes Spanner.

Pour vous authentifier auprès de Spanner, configurez les Identifiants par défaut de l'application. Pour en savoir plus, consultez Configurer l'authentification pour un environnement de développement local.

void QueryWithStringParameter(google::cloud::spanner::Client client) {
  namespace spanner = ::google::cloud::spanner;
  std::string example_string = "Venue 42";
  spanner::SqlStatement select(
      "SELECT VenueId, VenueName FROM Venues"
      " WHERE VenueName = @venue_name",
      {{"venue_name", spanner::Value(example_string)}});
  using RowType = std::tuple<std::int64_t, absl::optional<std::string>>;
  auto rows = client.ExecuteQuery(std::move(select));
  for (auto& row : spanner::StreamOf<RowType>(rows)) {
    if (!row) throw std::move(row).status();
    std::cout << "VenueId: " << std::get<0>(*row) << "\t";
    std::cout << "VenueName: " << std::get<1>(*row).value() << "\n";
  }
  std::cout << "Query completed for [spanner_query_with_string_parameter]\n";
}

C#

Pour savoir comment installer et utiliser la bibliothèque cliente pour Spanner, consultez la page Bibliothèques clientes Spanner.


using Google.Cloud.Spanner.Data;
using System.Collections.Generic;
using System.Threading.Tasks;

public class QueryWithStringAsyncSample
{
    public class Venue
    {
        public int VenueId { get; set; }
        public string VenueName { get; set; }
    }

    public async Task<List<Venue>> QueryWithStringAsync(string projectId, string instanceId, string databaseId)
    {
        string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";
        // Initialize a string variable to use for querying.
        string exampleString = "Venue 42";

        using var connection = new SpannerConnection(connectionString);
        var cmd = connection.CreateSelectCommand("SELECT VenueId, VenueName FROM Venues WHERE VenueName = @ExampleString");
        cmd.Parameters.Add("ExampleString", SpannerDbType.String, exampleString);

        var venues = new List<Venue>();
        using var reader = await cmd.ExecuteReaderAsync();
        while (await reader.ReadAsync())
        {
            venues.Add(new Venue
            {
                VenueId = reader.GetFieldValue<int>("VenueId"),
                VenueName = reader.GetFieldValue<string>("VenueName")
            });
        }
        return venues;
    }
}

Go

Pour savoir comment installer et utiliser la bibliothèque cliente pour Spanner, consultez la page Bibliothèques clientes Spanner.


import (
	"context"
	"fmt"
	"io"

	"cloud.google.com/go/spanner"
	"google.golang.org/api/iterator"
)

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

	var exampleString = "Venue 42"
	stmt := spanner.Statement{
		SQL: `SELECT VenueId, VenueName FROM Venues
            	WHERE VenueName = @venueName`,
		Params: map[string]interface{}{
			"venueName": exampleString,
		},
	}
	iter := client.Single().Query(ctx, stmt)
	defer iter.Stop()
	for {
		row, err := iter.Next()
		if err == iterator.Done {
			return nil
		}
		if err != nil {
			return err
		}
		var venueID int64
		var venueName string
		if err := row.Columns(&venueID, &venueName); err != nil {
			return err
		}
		fmt.Fprintf(w, "%d %s\n", venueID, venueName)
	}
}

Java

Pour savoir comment installer et utiliser la bibliothèque cliente pour Spanner, consultez la page Bibliothèques clientes Spanner.

static void queryWithString(DatabaseClient dbClient) {
  String exampleString = "Venue 42";
  Statement statement =
      Statement.newBuilder(
              "SELECT VenueId, VenueName FROM Venues " + "WHERE VenueName = @venueName")
          .bind("venueName")
          .to(exampleString)
          .build();
  try (ResultSet resultSet = dbClient.singleUse().executeQuery(statement)) {
    while (resultSet.next()) {
      System.out.printf(
          "%d %s\n", resultSet.getLong("VenueId"), resultSet.getString("VenueName"));
    }
  }
}

Node.js

Pour savoir comment installer et utiliser la bibliothèque cliente pour Spanner, consultez la page Bibliothèques clientes Spanner.

// 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 fieldType = {
  type: 'string',
};

const exampleString = 'Venue 42';

const query = {
  sql: `SELECT VenueId, VenueName FROM Venues
          WHERE VenueName = @venueName`,
  params: {
    venueName: exampleString,
  },
  types: {
    venueName: fieldType,
  },
};

// Queries rows from the Venues table.
try {
  const [rows] = await database.run(query);

  rows.forEach(row => {
    const json = row.toJSON();
    console.log(`VenueId: ${json.VenueId}, VenueName: ${json.VenueName}`);
  });
} catch (err) {
  console.error('ERROR:', err);
} finally {
  // Close the database when finished.
  database.close();
}

PHP

Pour savoir comment installer et utiliser la bibliothèque cliente pour Spanner, consultez la page Bibliothèques clientes Spanner.

use Google\Cloud\Spanner\SpannerClient;
use Google\Cloud\Spanner\Database;

/**
 * Queries sample data from the database using SQL with a STRING parameter.
 * Example:
 * ```
 * query_data_with_string_parameter($instanceId, $databaseId);
 * ```
 *
 * @param string $instanceId The Spanner instance ID.
 * @param string $databaseId The Spanner database ID.
 */
function query_data_with_string_parameter(string $instanceId, string $databaseId): void
{
    $spanner = new SpannerClient();
    $instance = $spanner->instance($instanceId);
    $database = $instance->database($databaseId);

    $exampleString = 'Venue 42';

    $results = $database->execute(
        'SELECT VenueId, VenueName FROM Venues ' .
        'WHERE VenueName = @venueName',
        [
            'parameters' => [
                'venueName' => $exampleString
            ]
        ]
    );

    foreach ($results as $row) {
        printf('VenueId: %s, VenueName: %s' . PHP_EOL,
            $row['VenueId'], $row['VenueName']);
    }
}

Python

Pour savoir comment installer et utiliser la bibliothèque cliente pour Spanner, consultez la page Bibliothèques clientes Spanner.

# 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)

exampleString = "Venue 42"
param = {"venue_name": exampleString}
param_type = {"venue_name": param_types.STRING}

with database.snapshot() as snapshot:
    results = snapshot.execute_sql(
        "SELECT VenueId, VenueName FROM Venues " "WHERE VenueName = @venue_name",
        params=param,
        param_types=param_type,
    )

    for row in results:
        print("VenueId: {}, VenueName: {}".format(*row))

Ruby

Pour savoir comment installer et utiliser la bibliothèque cliente pour Spanner, consultez la page Bibliothèques clientes Spanner.

# 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

sql_query = "SELECT VenueId, VenueName FROM Venues
             WHERE VenueName = @venue_name"

params      = { venue_name: "Venue 42" }
param_types = { venue_name: :STRING }

client.execute(sql_query, params: params, types: param_types).rows.each do |row|
  puts "#{row[:VenueId]} #{row[:VenueName]}"
end

Étapes suivantes

Pour rechercher et filtrer des exemples de code pour d'autres produits Google Cloud, consultez l'exemple de navigateur Google Cloud.