使用函数进行连接。
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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
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。
// Package spanner contains an example of using Spanner from a Cloud Function.
package spanner
import (
"context"
"fmt"
"log"
"net/http"
"sync"
"cloud.google.com/go/spanner"
"google.golang.org/api/iterator"
)
// client is a global Spanner client, to avoid initializing a new client for
// every request.
var client *spanner.Client
var clientOnce sync.Once
// db is the name of the database to query.
var db = "projects/my-project/instances/my-instance/databases/example-db"
// HelloSpanner is an example of querying Spanner from a Cloud Function.
func HelloSpanner(w http.ResponseWriter, r *http.Request) {
clientOnce.Do(func() {
// Declare a separate err variable to avoid shadowing client.
var err error
client, err = spanner.NewClient(context.Background(), db)
if err != nil {
http.Error(w, "Error initializing database", http.StatusInternalServerError)
log.Printf("spanner.NewClient: %v", err)
return
}
})
fmt.Fprintln(w, "Albums:")
stmt := spanner.Statement{SQL: `SELECT SingerId, AlbumId, AlbumTitle FROM Albums`}
iter := client.Single().Query(r.Context(), stmt)
defer iter.Stop()
for {
row, err := iter.Next()
if err == iterator.Done {
return
}
if err != nil {
http.Error(w, "Error querying database", http.StatusInternalServerError)
log.Printf("iter.Next: %v", err)
return
}
var singerID, albumID int64
var albumTitle string
if err := row.Columns(&singerID, &albumID, &albumTitle); err != nil {
http.Error(w, "Error parsing database response", http.StatusInternalServerError)
log.Printf("row.Columns: %v", err)
return
}
fmt.Fprintf(w, "%d %d %s\n", singerID, albumID, albumTitle)
}
}
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。
import com.google.api.client.http.HttpStatusCodes;
import com.google.cloud.functions.HttpFunction;
import com.google.cloud.functions.HttpRequest;
import com.google.cloud.functions.HttpResponse;
import com.google.cloud.spanner.DatabaseClient;
import com.google.cloud.spanner.DatabaseId;
import com.google.cloud.spanner.LazySpannerInitializer;
import com.google.cloud.spanner.ResultSet;
import com.google.cloud.spanner.SpannerException;
import com.google.cloud.spanner.SpannerOptions;
import com.google.cloud.spanner.Statement;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.MoreObjects;
import java.io.PrintWriter;
import java.util.logging.Level;
import java.util.logging.Logger;
// HelloSpanner is an example of querying Spanner from a Cloud Function.
public class HelloSpanner implements HttpFunction {
private static final Logger logger = Logger.getLogger(HelloSpanner.class.getName());
// TODO<developer>: Set these environment variables.
private static final String SPANNER_INSTANCE_ID =
MoreObjects.firstNonNull(System.getenv("SPANNER_INSTANCE"), "my-instance");
private static final String SPANNER_DATABASE_ID =
MoreObjects.firstNonNull(System.getenv("SPANNER_DATABASE"), "example-db");
private static final DatabaseId databaseId =
DatabaseId.of(
SpannerOptions.getDefaultProjectId(),
SPANNER_INSTANCE_ID,
SPANNER_DATABASE_ID);
// The LazySpannerInitializer instance is shared across all instances of the HelloSpanner class.
// It will create a Spanner instance the first time one is requested, and continue to return that
// instance for all subsequent requests.
private static final LazySpannerInitializer SPANNER_INITIALIZER = new LazySpannerInitializer();
@VisibleForTesting
DatabaseClient getClient() throws Throwable {
return SPANNER_INITIALIZER.get().getDatabaseClient(databaseId);
}
@Override
public void service(HttpRequest request, HttpResponse response) throws Exception {
var writer = new PrintWriter(response.getWriter());
try {
DatabaseClient client = getClient();
try (ResultSet rs =
client
.singleUse()
.executeQuery(Statement.of("SELECT SingerId, AlbumId, AlbumTitle FROM Albums"))) {
writer.printf("Albums:%n");
while (rs.next()) {
writer.printf(
"%d %d %s%n",
rs.getLong("SingerId"), rs.getLong("AlbumId"), rs.getString("AlbumTitle"));
}
} catch (SpannerException e) {
writer.printf("Error querying database: %s%n", e.getMessage());
response.setStatusCode(HttpStatusCodes.STATUS_CODE_SERVER_ERROR, e.getMessage());
}
} catch (Throwable t) {
logger.log(Level.SEVERE, "Spanner example failed", t);
writer.printf("Error setting up Spanner: %s%n", t.getMessage());
response.setStatusCode(HttpStatusCodes.STATUS_CODE_SERVER_ERROR, t.getMessage());
}
}
}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。
// Imports the Google Cloud client library
const {Spanner} = require('@google-cloud/spanner');
// Instantiates a client
const spanner = new Spanner();
// Your Cloud Spanner instance ID
const instanceId = 'test-instance';
// Your Cloud Spanner database ID
const databaseId = 'example-db';
/**
* HTTP Cloud Function.
*
* @param {Object} req Cloud Function request context.
* @param {Object} res Cloud Function response context.
*/
exports.get = async (req, res) => {
// Gets a reference to a Cloud Spanner instance and database
const instance = spanner.instance(instanceId);
const database = instance.database(databaseId);
// The query to execute
const query = {
sql: 'SELECT * FROM Albums',
};
// Execute the query
try {
const results = await database.run(query);
const rows = results[0].map(row => row.toJSON());
rows.forEach(row => {
res.write(
`SingerId: ${row.SingerId}, ` +
`AlbumId: ${row.AlbumId}, ` +
`AlbumTitle: ${row.AlbumTitle}\n`
);
});
res.status(200).end();
} catch (err) {
res.status(500).send(`Error querying Spanner: ${err}`);
}
};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。
from google.cloud import spanner
instance_id = 'test-instance'
database_id = 'example-db'
client = spanner.Client()
instance = client.instance(instance_id)
database = instance.database(database_id)
def spanner_read_data(request):
query = 'SELECT * FROM Albums'
outputs = []
with database.snapshot() as snapshot:
results = snapshot.execute_sql(query)
for row in results:
output = 'SingerId: {}, AlbumId: {}, AlbumTitle: {}'.format(*row)
outputs.append(output)
return '\n'.join(outputs)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。