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DatabaseSelect.java
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DatabaseSelect.java
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/*
* Copyright 2017 Google LLC
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* EDITING INSTRUCTIONS
* This file is referenced in READMEs. Any change to this file should be reflected in
* the project's READMEs.
*/
package com.google.cloud.examples.spanner.snippets;
import com.google.cloud.spanner.DatabaseClient;
import com.google.cloud.spanner.DatabaseId;
import com.google.cloud.spanner.ResultSet;
import com.google.cloud.spanner.Spanner;
import com.google.cloud.spanner.SpannerOptions;
import com.google.cloud.spanner.Statement;
/**
* A quick start code for Cloud Spanner. It demonstrates how to setup the Cloud Spanner client and
* execute a simple query using it against an existing database.
*/
public class DatabaseSelect {
public static void main(String... args) throws Exception {
if (args.length != 2) {
System.err.println("Usage: QuickStartSample <instance_id> <database_id>");
return;
}
// Instantiates a client
SpannerOptions options = SpannerOptions.newBuilder().build();
Spanner spanner = options.getService();
// Name of your instance & database.
String instanceId = args[0];
String databaseId = args[1];
try {
// Creates a database client
DatabaseClient dbClient =
spanner.getDatabaseClient(DatabaseId.of(options.getProjectId(), instanceId, databaseId));
// Queries the database
try (ResultSet resultSet = dbClient.singleUse().executeQuery(Statement.of("SELECT 1"))) {
System.out.println("\n\nResults:");
// Prints the results
while (resultSet.next()) {
System.out.printf("%d\n\n", resultSet.getLong(0));
}
}
} finally {
// Closes the client which will free up the resources used
spanner.close();
}
}
}