Query data with STRUCT

Query data by using a STRUCT object.

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For detailed documentation that includes this code sample, see the following:

Code sample

C++

To learn how to install and use the client library for Spanner, see Spanner client libraries.

To authenticate to Spanner, set up Application Default Credentials. For more information, see Set up authentication for a local development environment. 

void QueryDataWithStruct(google::cloud::spanner::Client client) {
  namespace spanner = ::google::cloud::spanner;
  // Cloud Spanner STRUCT<> types are represented by std::tuple<...>. The
  // following represents a STRUCT<> with two unnamed STRING fields.
  using NameType = std::tuple<std::string, std::string>;
  auto singer_info = NameType{"Elena", "Campbell"};
  auto rows = client.ExecuteQuery(spanner::SqlStatement(
      "SELECT SingerId FROM Singers WHERE (FirstName, LastName) = @name",
      {{"name", spanner::Value(singer_info)}}));
  //! [spanner-sql-statement-params]

  for (auto& row : spanner::StreamOf<std::tuple<std::int64_t>>(rows)) {
    if (!row) throw std::move(row).status();
    std::cout << "SingerId: " << std::get<0>(*row) << "\n";
  }
  std::cout << "Query completed for [spanner_query_data_with_struct]\n";
}

C#

To learn how to install and use the client library for Spanner, see Spanner client libraries.

To authenticate to Spanner, set up Application Default Credentials. For more information, see Set up authentication for a local development environment. 


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

public class QueryDataWithStructAsyncSample
{
    public async Task<List<int>> QueryDataWithStructAsync(string projectId, string instanceId, string databaseId)
    {
        var nameStruct = new SpannerStruct
        {
            { "FirstName", SpannerDbType.String, "Elena" },
            { "LastName", SpannerDbType.String, "Campbell" },
        };

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

        var singerIds = new List<int>();
        using var connection = new SpannerConnection(connectionString);
        using var cmd = connection.CreateSelectCommand(
            "SELECT SingerId FROM Singers "
            + "WHERE STRUCT<FirstName STRING, LastName STRING>"
            + "(FirstName, LastName) = @name");

        cmd.Parameters.Add("name", nameStruct.GetSpannerDbType(), nameStruct);
        using var reader = await cmd.ExecuteReaderAsync();
        while (await reader.ReadAsync())
        {
            singerIds.Add(reader.GetFieldValue<int>("SingerId"));
        }
        return singerIds;
    }
}

Go

To learn how to install and use the client library for Spanner, see Spanner client libraries.

To authenticate to Spanner, set up Application Default Credentials. For more information, see Set up authentication for a local development environment. 


stmt := spanner.Statement{
	SQL: `SELECT SingerId FROM SINGERS
			WHERE (FirstName, LastName) = @singerinfo`,
	Params: map[string]interface{}{"singerinfo": singerInfo},
}
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 singerID int64
	if err := row.Columns(&singerID); err != nil {
		return err
	}
	fmt.Fprintf(w, "%d\n", singerID)
}

Java

To learn how to install and use the client library for Spanner, see Spanner client libraries.

To authenticate to Spanner, set up Application Default Credentials. For more information, see Set up authentication for a local development environment. 

Statement s =
    Statement.newBuilder(
            "SELECT SingerId FROM Singers "
                + "WHERE STRUCT<FirstName STRING, LastName STRING>(FirstName, LastName) "
                + "= @name")
        .bind("name")
        .to(name)
        .build();
try (ResultSet resultSet = dbClient.singleUse().executeQuery(s)) {
  while (resultSet.next()) {
    System.out.printf("%d\n", resultSet.getLong("SingerId"));
  }
}

Node.js

To learn how to install and use the client library for Spanner, see Spanner client libraries.

To authenticate to Spanner, set up Application Default Credentials. For more information, see Set up authentication for a local development environment. 

/**
 * 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 query = {
  sql:
    'SELECT SingerId FROM Singers WHERE ' +
    'STRUCT<FirstName STRING, LastName STRING>(FirstName, LastName) = @name',
  params: {
    name: nameStruct,
  },
};

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

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

PHP

To learn how to install and use the client library for Spanner, see Spanner client libraries.

To authenticate to Spanner, set up Application Default Credentials. For more information, see Set up authentication for a local development environment. 

$results = $database->execute(
    'SELECT SingerId FROM Singers ' .
    'WHERE STRUCT<FirstName STRING, LastName STRING>' .
    '(FirstName, LastName) = @name',
    [
        'parameters' => [
            'name' => $nameValue
        ],
        'types' => [
            'name' => $nameType
        ]
    ]
);
foreach ($results as $row) {
    printf('SingerId: %s' . PHP_EOL,
        $row['SingerId']);
}

Python

To learn how to install and use the client library for Spanner, see Spanner client libraries.

To authenticate to Spanner, set up Application Default Credentials. For more information, see Set up authentication for a local development environment. 

spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)

database = instance.database(database_id)

with database.snapshot() as snapshot:
    results = snapshot.execute_sql(
        "SELECT SingerId FROM Singers WHERE " "(FirstName, LastName) = @name",
        params={"name": record_value},
        param_types={"name": record_type},
    )

for row in results:
    print("SingerId: {}".format(*row))

Ruby

To learn how to install and use the client library for Spanner, see Spanner client libraries.

To authenticate to Spanner, set up Application Default Credentials. For more information, see Set up authentication for a local development environment. 

# 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.execute(
  "SELECT SingerId FROM Singers WHERE " +
  "(FirstName, LastName) = @name",
  params: { name: name_struct }
).rows.each do |row|
  puts row[:SingerId]
end

What's next

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