Introduction to SQL in BigQuery

This document provides an overview of supported statements and SQL dialects in BigQuery.

GoogleSQL is an ANSI-compliant Structured Query Language (SQL) that includes the following types of supported statements:

BigQuery SQL dialects

BigQuery supports the GoogleSQL dialect, but a legacy SQL dialect is also available. If you are new to BigQuery, you should use GoogleSQL as it supports the broadest range of functionality. For example, features such as DDL and DML statements are only supported using GoogleSQL. Legacy SQL is maintained for backward compatibility and we recommend that customers migrate if they are using legacy SQL.

Changing from the default dialect

The interface you use to query your data determines which query dialect is the default. To switch to a different dialect:

Console

The default dialect for the Google Cloud console is GoogleSQL. To change the dialect to legacy SQL:

  1. In the Google Cloud console, go to the BigQuery page.

    Go to BigQuery

  2. In the query editor, click the More > Query settings button.

  3. In the Advanced options section, for SQL dialect, click Legacy, then click Save. This sets the legacy SQL option for this query. When you click add_boxSQL Query to create a new query, you must select the legacy SQL option again.

SQL

The default SQL dialect is GoogleSQL. You can set the SQL dialect by including the prefix #standardSQL or #legacySQL as part of your query. These query prefixes are not case-sensitive, must precede the query, and must be separated from the query by a newline character. The following example sets the dialect to legacy SQL and queries the natality dataset:

  1. In the Google Cloud console, go to the BigQuery Studio page.

    Go to BigQuery Studio

  2. In the query editor, enter the following statement:

    #legacySQLSELECTweight_pounds,state,year,gestation_weeksFROM[bigquery-public-data:samples.natality]ORDERBYweight_poundsDESCLIMIT10;

  3. Click Run.

For more information about how to run queries, see Run an interactive query.

bq

The default query dialect in the bq command-line tool is legacy SQL. To switch to the GoogleSQL dialect, add the --use_legacy_sql=false or --nouse_legacy_sql flag to your command-line statement.

Switch to the GoogleSQL dialect

To use GoogleSQL syntax in a query job, set the use_legacy_sql parameter to false.

bqquery\--use_legacy_sql=false\'SELECT word FROM `bigquery-public-data.samples.shakespeare`'

Set GoogleSQL as the default dialect

You can set GoogleSQL as the default dialect for the command-line tool and the interactive shell by editing the command-line tool's configuration file: .bigqueryrc.

For more information on .bigqueryrc, see Setting default values for command-specific flags.

To set --use_legacy_sql=false in .bigqueryrc:

  1. Open .bigqueryrc in a text editor. By default, .bigqueryrc should be in your user directory, for example, $HOME/.bigqueryrc.

  2. Add the following text to the file. This example sets GoogleSQL as the default syntax for queries and for the mk command (used when you create a view). If you have already configured default values for query or mk command flags, you do not need to add [query] or [mk] again.

    [query]--use_legacy_sql=false[mk]--use_legacy_sql=false

  3. Save and close the file.

  4. If you are using the interactive shell, you must exit and restart for the changes to be applied.

For information on available command-line flags, see bq command-line tool reference.

C#

Before trying this sample, follow the C# setup instructions in the BigQuery quickstart using client libraries. For more information, see the BigQuery C# API reference documentation.

To authenticate to BigQuery, set up Application Default Credentials. For more information, see Set up authentication for client libraries.

By default, the C# library uses GoogleSQL.

Switch to the legacy SQL dialect

To use legacy SQL syntax in a query job, set the UseLegacySql parameter to true.

usingGoogle.Cloud.BigQuery.V2;usingSystem;publicclassBigQueryQueryLegacy{publicvoidQueryLegacy(stringprojectId="your-project-id"){BigQueryClientclient=BigQueryClient.Create(projectId);stringquery=@" SELECT name FROM [bigquery-public-data:usa_names.usa_1910_2013] WHERE state = 'TX' LIMIT 100";BigQueryJobjob=client.CreateQueryJob(sql:query,parameters:null,options:newQueryOptions{UseLegacySql=true});// Wait for the job to complete.job=job.PollUntilCompleted().ThrowOnAnyError();// Display the resultsforeach(BigQueryRowrowinclient.GetQueryResults(job.Reference)){Console.WriteLine($"{row["name"]}");}}}

Go

Before trying this sample, follow the Go setup instructions in the BigQuery quickstart using client libraries. For more information, see the BigQuery Go API reference documentation.

To authenticate to BigQuery, set up Application Default Credentials. For more information, see Set up authentication for client libraries.

By default, the Go client library uses GoogleSQL.

Switch to the legacy SQL dialect

To use legacy SQL syntax in a query job, set the UseLegacySQL property within the query configuration to true.

import("context""fmt""io""cloud.google.com/go/bigquery""google.golang.org/api/iterator")// queryLegacy demonstrates running a query using Legacy SQL.funcqueryLegacy(wio.Writer,projectID,sqlStringstring)error{// projectID := "my-project-id"// sqlString = "SELECT 3 as somenum"ctx:=context.Background()client,err:=bigquery.NewClient(ctx,projectID)iferr!=nil{returnfmt.Errorf("bigquery.NewClient: %w",err)}deferclient.Close()q:=client.Query(sqlString)q.UseLegacySQL=true// Run the query and process the returned row iterator.it,err:=q.Read(ctx)iferr!=nil{returnfmt.Errorf("query.Read(): %w",err)}for{varrow[]bigquery.Valueerr:=it.Next(&row)iferr==iterator.Done{break}iferr!=nil{returnerr}fmt.Fprintln(w,row)}returnnil}

Java

Before trying this sample, follow the Java setup instructions in the BigQuery quickstart using client libraries. For more information, see the BigQuery Java API reference documentation.

To authenticate to BigQuery, set up Application Default Credentials. For more information, see Set up authentication for client libraries.

By default, the Java client library uses GoogleSQL.

Switch to the legacy SQL dialect

To use legacy SQL syntax in a query job, set the useLegacySql parameter to true.

importcom.google.cloud.bigquery.BigQuery;importcom.google.cloud.bigquery.BigQueryException;importcom.google.cloud.bigquery.BigQueryOptions;importcom.google.cloud.bigquery.QueryJobConfiguration;importcom.google.cloud.bigquery.TableResult;publicclassRunLegacyQuery{publicstaticvoidmain(String[]args){runLegacyQuery();}publicstaticvoidrunLegacyQuery(){try{// Initialize client that will be used to send requests. This client only needs to be created// once, and can be reused for multiple requests.BigQuerybigquery=BigQueryOptions.getDefaultInstance().getService();// To use legacy SQL syntax, set useLegacySql to true.Stringquery="SELECT corpus FROM [bigquery-public-data:samples.shakespeare] GROUP BY corpus;";QueryJobConfigurationqueryConfig=QueryJobConfiguration.newBuilder(query).setUseLegacySql(true).build();// Execute the query.TableResultresult=bigquery.query(queryConfig);// Print the results.result.iterateAll().forEach(rows->rows.forEach(row->System.out.println(row.getValue())));System.out.println("Legacy query ran successfully");}catch(BigQueryException|InterruptedExceptione){System.out.println("Legacy query did not run \n"+e.toString());}}}

Node.js

Before trying this sample, follow the Node.js setup instructions in the BigQuery quickstart using client libraries. For more information, see the BigQuery Node.js API reference documentation.

To authenticate to BigQuery, set up Application Default Credentials. For more information, see Set up authentication for client libraries.

By default, the Node.js client library uses GoogleSQL.

Switch to the legacy SQL dialect

To use legacy SQL syntax in a query job, set the useLegacySql parameter to true.

// Import the Google Cloud client libraryconst{BigQuery}=require('@google-cloud/bigquery');constbigquery=newBigQuery();asyncfunctionqueryLegacy(){// Queries the U.S. given names dataset for the state of Texas using legacy SQL.constquery='SELECT word FROM [bigquery-public-data:samples.shakespeare] LIMIT 10;';// For all options, see https://cloud.google.com/bigquery/docs/reference/rest/v2/jobs/queryconstoptions={query:query,// Location must match that of the dataset(s) referenced in the query.location:'US',useLegacySql:true,};// Run the query as a jobconst[job]=awaitbigquery.createQueryJob(options);console.log(`Job ${job.id} started.`);// Wait for the query to finishconst[rows]=awaitjob.getQueryResults();// Print the resultsconsole.log('Rows:');rows.forEach(row=>console.log(row));}

PHP

Before trying this sample, follow the PHP setup instructions in the BigQuery quickstart using client libraries. For more information, see the BigQuery PHP API reference documentation.

To authenticate to BigQuery, set up Application Default Credentials. For more information, see Set up authentication for client libraries.

By default, the PHP client library uses GoogleSQL.

Switch to the legacy SQL dialect

To use legacy SQL syntax in a query job, set the useLegacySql parameter to true.

use Google\Cloud\BigQuery\BigQueryClient;/** * Query using legacy sql * * @param string $projectId The project Id of your Google Cloud Project. */function query_legacy(string $projectId): void{ $query = 'SELECT corpus FROM [bigquery-public-data:samples.shakespeare] GROUP BY corpus'; $bigQuery = new BigQueryClient([ 'projectId' => $projectId, ]); $jobConfig = $bigQuery->query($query)->useLegacySql(true); $queryResults = $bigQuery->runQuery($jobConfig); $i = 0; foreach ($queryResults as $row) { printf('--- Row %s ---' . PHP_EOL, ++$i); foreach ($row as $column => $value) { printf('%s: %s' . PHP_EOL, $column, json_encode($value)); } } printf('Found %s row(s)' . PHP_EOL, $i);}

Python

Before trying this sample, follow the Python setup instructions in the BigQuery quickstart using client libraries. For more information, see the BigQuery Python API reference documentation.

To authenticate to BigQuery, set up Application Default Credentials. For more information, see Set up authentication for client libraries.

By default, the Python client library uses GoogleSQL.

Switch to the legacy SQL dialect

To use legacy SQL syntax in a query job, set the use_legacy_sql parameter to True.

fromgoogle.cloudimportbigquery# Construct a BigQuery client object.client=bigquery.Client()query=("SELECT name FROM [bigquery-public-data:usa_names.usa_1910_2013] "'WHERE state = "TX" '"LIMIT 100")# Set use_legacy_sql to True to use legacy SQL syntax.job_config=bigquery.QueryJobConfig(use_legacy_sql=True)# Start the query and waits for query job to complete, passing in the extra configuration.results=client.query_and_wait(query,job_config=job_config)# Make an API request.print("The query data:")forrowinresults:print(row)

Ruby

Before trying this sample, follow the Ruby setup instructions in the BigQuery quickstart using client libraries. For more information, see the BigQuery Ruby API reference documentation.

To authenticate to BigQuery, set up Application Default Credentials. For more information, see Set up authentication for client libraries.

By default, the Ruby client library uses GoogleSQL.

Switch to the legacy SQL dialect

To use legacy SQL syntax in a query job, pass the option legacy_sql: true with your query.

require"google/cloud/bigquery"defquery_legacybigquery=Google::Cloud::Bigquery.newsql="SELECT name FROM [bigquery-public-data:usa_names.usa_1910_2013] "\"WHERE state = 'TX' "\"LIMIT 100"results=bigquery.querysql,legacy_sql:truedo|config|# Location must match that of the dataset(s) referenced in the query.config.location="US"endresults.eachdo|row|putsrow.inspectendend

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