Consulta con el parámetro FLOAT

Consulta datos mediante un parámetro FLOAT.

Muestra de código

C++

Para obtener información sobre cómo instalar y usar la biblioteca cliente de Spanner, consulta Bibliotecas cliente de Spanner.

Para autenticarte en Spanner, configura las credenciales predeterminadas de la aplicación. Si deseas obtener más información, consulta Configura la autenticación para un entorno de desarrollo local.

void QueryWithFloatParameter(google::cloud::spanner::Client client) {
  namespace spanner = ::google::cloud::spanner;
  double example_float = 0.8;
  spanner::SqlStatement select(
      "SELECT VenueId, VenueName, PopularityScore FROM Venues"
      " WHERE PopularityScore > @popularity_score",
      {{"popularity_score", spanner::Value(example_float)}});
  using RowType = std::tuple<std::int64_t, absl::optional<std::string>,
                             absl::optional<double>>;
  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() << "\t";
    std::cout << "PopularityScore: " << std::get<2>(*row).value() << "\n";
  }
  std::cout << "Query completed for [spanner_query_with_float_parameter]\n";
}

C#

Para obtener información sobre cómo instalar y usar la biblioteca cliente de Spanner, consulta Bibliotecas cliente de Spanner.


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

public class QueryWithFloatAsyncSample
{
    public class Venue
    {
        public int VenueId { get; set; }
        public string VenueName { get; set; }
        public float PopularityScore { get; set; }
    }

    public async Task<List<Venue>> QueryWithFloatAsync(string projectId, string instanceId, string databaseId)
    {
        string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";
        // Initialize a float variable to use for querying.
        float exampleFloat = 0.8f;

        using var connection = new SpannerConnection(connectionString);
        var cmd = connection.CreateSelectCommand("SELECT VenueId, VenueName, PopularityScore FROM Venues WHERE PopularityScore > @ExampleFloat");
        cmd.Parameters.Add("ExampleFloat", SpannerDbType.Float64, exampleFloat);

        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"),
                PopularityScore = reader.GetFieldValue<float>("PopularityScore")
            });
        }
        return venues;
    }
}

Go

Para obtener información sobre cómo instalar y usar la biblioteca cliente de Spanner, consulta Bibliotecas cliente de Spanner.


import (
	"context"
	"fmt"
	"io"

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

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

	var exampleFloat = 0.8
	stmt := spanner.Statement{
		SQL: `SELECT VenueId, VenueName, PopularityScore FROM Venues
            	WHERE PopularityScore > @popularityScore`,
		Params: map[string]interface{}{
			"popularityScore": exampleFloat,
		},
	}
	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
		var popularityScore float64
		if err := row.Columns(&venueID, &venueName, &popularityScore); err != nil {
			return err
		}
		fmt.Fprintf(w, "%d %s %f\n", venueID, venueName, popularityScore)
	}
}

Java

Para obtener información sobre cómo instalar y usar la biblioteca cliente de Spanner, consulta Bibliotecas cliente de Spanner.

static void queryWithFloat(DatabaseClient dbClient) {
  float exampleFloat = 0.8f;
  Statement statement =
      Statement.newBuilder(
              "SELECT VenueId, VenueName, PopularityScore FROM Venues "
                  + "WHERE PopularityScore > @popularityScore")
          .bind("popularityScore")
          .to(exampleFloat)
          .build();
  try (ResultSet resultSet = dbClient.singleUse().executeQuery(statement)) {
    while (resultSet.next()) {
      System.out.printf(
          "%d %s %f\n",
          resultSet.getLong("VenueId"),
          resultSet.getString("VenueName"),
          resultSet.getDouble("PopularityScore"));
    }
  }
}

Node.js

Para obtener información sobre cómo instalar y usar la biblioteca cliente de Spanner, consulta Bibliotecas cliente de 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: 'float64',
};

const exampleFloat = Spanner.float(0.8);

const query = {
  sql: `SELECT VenueId, VenueName, PopularityScore FROM Venues
          WHERE PopularityScore > @popularityScore`,
  params: {
    popularityScore: exampleFloat,
  },
  types: {
    popularityScore: 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},` +
        ` PopularityScore: ${json.PopularityScore}`
    );
  });
} catch (err) {
  console.error('ERROR:', err);
} finally {
  // Close the database when finished.
  database.close();
}

PHP

Para obtener información sobre cómo instalar y usar la biblioteca cliente de Spanner, consulta Bibliotecas cliente de Spanner.

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

/**
 * Queries sample data from the database using SQL with a FLOAT64 parameter.
 * Example:
 * ```
 * query_data_with_float_parameter($instanceId, $databaseId);
 * ```
 *
 * @param string $instanceId The Spanner instance ID.
 * @param string $databaseId The Spanner database ID.
 */
function query_data_with_float_parameter(string $instanceId, string $databaseId): void
{
    $spanner = new SpannerClient();
    $instance = $spanner->instance($instanceId);
    $database = $instance->database($databaseId);

    $exampleFloat = 0.8;

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

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

Python

Para obtener información sobre cómo instalar y usar la biblioteca cliente de Spanner, consulta Bibliotecas cliente de 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)

exampleFloat = 0.8
param = {"popularity_score": exampleFloat}
param_type = {"popularity_score": param_types.FLOAT64}

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

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

Ruby

Para obtener información sobre cómo instalar y usar la biblioteca cliente de Spanner, consulta Bibliotecas cliente de 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, PopularityScore FROM Venues
             WHERE PopularityScore > @popularity_score"

params      = { popularity_score: 0.8 }
param_types = { popularity_score: :FLOAT64 }

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

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