Run a query with named parameters.

## Explore further


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

- [Run parameterized queries](https://docs.cloud.google.com/bigquery/docs/parameterized-queries)

## Code sample

### C#


Before trying this sample, follow the C# setup instructions in the
[BigQuery quickstart using
client libraries](https://docs.cloud.google.com/bigquery/docs/quickstarts/quickstart-client-libraries).


For more information, see the
[BigQuery C# API
reference documentation](https://docs.cloud.google.com/dotnet/docs/reference/Google.Cloud.BigQuery.V2/latest).


To authenticate to BigQuery, set up Application Default Credentials.
For more information, see

[Set up authentication for client libraries](https://docs.cloud.google.com/bigquery/docs/authentication#client-libs).


    using https://docs.cloud.google.com/dotnet/docs/reference/Google.Cloud.BigQuery.V2/latest/Google.Cloud.BigQuery.V2.html;
    using System;

    public class BigQueryQueryWithNamedParameters
    {
        public void QueryWithNamedParameters(string projectId = "your-project-id")
        {
            var corpus = "romeoandjuliet";
            var minWordCount = 250;

            // Note: Standard SQL is required to use query parameters.
            var query = @"
                SELECT word, word_count
                FROM `bigquery-public-data.samples.shakespeare`
                WHERE corpus = @corpus
                AND word_count >= @min_word_count
                ORDER BY word_count DESC";

            // Initialize client that will be used to send requests.
            var client = https://docs.cloud.google.com/dotnet/docs/reference/Google.Cloud.BigQuery.V2/latest/Google.Cloud.BigQuery.V2.BigQueryClient.html.https://docs.cloud.google.com/dotnet/docs/reference/Google.Cloud.BigQuery.V2/latest/Google.Cloud.BigQuery.V2.BigQueryClient.html#Google_Cloud_BigQuery_V2_BigQueryClient_Create_System_String_Google_Apis_Auth_OAuth2_GoogleCredential_(projectId);

            var parameters = new https://docs.cloud.google.com/dotnet/docs/reference/Google.Cloud.BigQuery.V2/latest/Google.Cloud.BigQuery.V2.BigQueryParameter.html[]
            {
                new https://docs.cloud.google.com/dotnet/docs/reference/Google.Cloud.BigQuery.V2/latest/Google.Cloud.BigQuery.V2.BigQueryParameter.html("corpus", https://docs.cloud.google.com/dotnet/docs/reference/Google.Cloud.BigQuery.V2/latest/Google.Cloud.BigQuery.V2.BigQueryDbType.html.https://docs.cloud.google.com/dotnet/docs/reference/Google.Cloud.BigQuery.V2/latest/Google.Cloud.BigQuery.V2.BigQueryDbType.html#Google_Cloud_BigQuery_V2_BigQueryDbType_String, corpus),
                new https://docs.cloud.google.com/dotnet/docs/reference/Google.Cloud.BigQuery.V2/latest/Google.Cloud.BigQuery.V2.BigQueryParameter.html("min_word_count", https://docs.cloud.google.com/dotnet/docs/reference/Google.Cloud.BigQuery.V2/latest/Google.Cloud.BigQuery.V2.BigQueryDbType.html.https://docs.cloud.google.com/dotnet/docs/reference/Google.Cloud.BigQuery.V2/latest/Google.Cloud.BigQuery.V2.BigQueryDbType.html#Google_Cloud_BigQuery_V2_BigQueryDbType_Int64, minWordCount)
            };

            var job = client.CreateQueryJob(
                sql: query,
                parameters: parameters,
                options: new https://docs.cloud.google.com/dotnet/docs/reference/Google.Cloud.BigQuery.V2/latest/Google.Cloud.BigQuery.V2.QueryOptions.html { UseQueryCache = false });
            // Wait for the job to complete.
            job = job.https://docs.cloud.google.com/dotnet/docs/reference/Google.Cloud.BigQuery.V2/latest/Google.Cloud.BigQuery.V2.BigQueryJob.html#Google_Cloud_BigQuery_V2_BigQueryJob_PollUntilCompleted_Google_Cloud_BigQuery_V2_GetJobOptions_Google_Api_Gax_PollSettings_().ThrowOnAnyError();
            // Display the results
            foreach (https://docs.cloud.google.com/dotnet/docs/reference/Google.Cloud.BigQuery.V2/latest/Google.Cloud.BigQuery.V2.BigQueryRow.html row in client.GetQueryResults(job.Reference))
            {
                Console.WriteLine($"{row["word"]}: {row["word_count"]}");
            }
        }
    }

### Go


Before trying this sample, follow the Go setup instructions in the
[BigQuery quickstart using
client libraries](https://docs.cloud.google.com/bigquery/docs/quickstarts/quickstart-client-libraries).


For more information, see the
[BigQuery Go API
reference documentation](https://godoc.org/cloud.google.com/go/bigquery).


To authenticate to BigQuery, set up Application Default Credentials.
For more information, see

[Set up authentication for client libraries](https://docs.cloud.google.com/bigquery/docs/authentication#client-libs).

    import (
    	"context"
    	"fmt"
    	"io"

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

    // queryWithNamedParams demonstrate issuing a query using named query parameters.
    func queryWithNamedParams(w io.Writer, projectID string) error {
    	// projectID := "my-project-id"
    	ctx := context.Background()
    	client, err := bigquery.NewClient(ctx, projectID)
    	if err != nil {
    		return fmt.Errorf("bigquery.NewClient: %w", err)
    	}
    	defer client.Close()

    	q := client.Query(
    		`SELECT word, word_count
            FROM ` + "`bigquery-public-data.samples.shakespeare`" + `
            WHERE corpus = @corpus
            AND word_count >= @min_word_count
            ORDER BY word_count DESC;`)
    	q.Parameters = []bigquery.https://docs.cloud.google.com/go/docs/reference/cloud.google.com/go/bigquery/latest/index.html#cloud_google_com_go_bigquery_QueryParameter{
    		{
    			Name:  "corpus",
    			Value: "romeoandjuliet",
    		},
    		{
    			Name:  "min_word_count",
    			Value: 250,
    		},
    	}
    	// Run the query and process the returned row iterator.
    	it, err := q.Read(ctx)
    	if err != nil {
    		return fmt.Errorf("query.Read(): %w", err)
    	}
    	for {
    		var row []bigquery.https://docs.cloud.google.com/go/docs/reference/cloud.google.com/go/bigquery/latest/index.html#cloud_google_com_go_bigquery_Value
    		err := it.Next(&row)
    		if err == iterator.Done {
    			break
    		}
    		if err != nil {
    			return err
    		}
    		fmt.Fprintln(w, row)
    	}
    	return nil
    }

### Java


Before trying this sample, follow the Java setup instructions in the
[BigQuery quickstart using
client libraries](https://docs.cloud.google.com/bigquery/docs/quickstarts/quickstart-client-libraries).


For more information, see the
[BigQuery Java API
reference documentation](https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/overview).


To authenticate to BigQuery, set up Application Default Credentials.
For more information, see

[Set up authentication for client libraries](https://docs.cloud.google.com/bigquery/docs/authentication#client-libs).

    import com.google.cloud.bigquery.https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.BigQuery.html;
    import com.google.cloud.bigquery.https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.BigQueryException.html;
    import com.google.cloud.bigquery.https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.BigQueryOptions.html;
    import com.google.cloud.bigquery.https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.QueryJobConfiguration.html;
    import com.google.cloud.bigquery.https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.QueryParameterValue.html;
    import com.google.cloud.bigquery.https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.TableResult.html;

    public class QueryWithNamedParameters {

      public static void main(String[] args) {
        queryWithNamedParameters();
      }

      public static void queryWithNamedParameters() {
        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.
          https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.BigQuery.html bigquery = https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.BigQueryOptions.html.getDefaultInstance().getService();

          String corpus = "romeoandjuliet";
          long minWordCount = 250;
          String query =
              "SELECT word, word_count\n"
                  + "FROM `bigquery-public-data.samples.shakespeare`\n"
                  + "WHERE corpus = @corpus\n"
                  + "AND word_count >= @min_word_count\n"
                  + "ORDER BY word_count DESC";

          // Note: Standard SQL is required to use query parameters.
          https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.QueryJobConfiguration.html queryConfig =
              https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.QueryJobConfiguration.html.newBuilder(query)
                  .https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.QueryJobConfiguration.Builder.html#com_google_cloud_bigquery_QueryJobConfiguration_Builder_addNamedParameter_java_lang_String_com_google_cloud_bigquery_QueryParameterValue_("corpus", https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.QueryParameterValue.html.https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.QueryParameterValue.html#com_google_cloud_bigquery_QueryParameterValue_string_java_lang_String_(corpus))
                  .https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.QueryJobConfiguration.Builder.html#com_google_cloud_bigquery_QueryJobConfiguration_Builder_addNamedParameter_java_lang_String_com_google_cloud_bigquery_QueryParameterValue_("min_word_count", https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.QueryParameterValue.html.https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.QueryParameterValue.html#com_google_cloud_bigquery_QueryParameterValue_int64_java_lang_Integer_(minWordCount))
                  .build();

          https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.TableResult.html results = bigquery.https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.BigQuery.html#com_google_cloud_bigquery_BigQuery_query_com_google_cloud_bigquery_QueryJobConfiguration_com_google_cloud_bigquery_BigQuery_JobOption____(queryConfig);

          results
              .https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.TableResult.html#com_google_cloud_bigquery_TableResult_iterateAll__()
              .forEach(row -> row.forEach(val -> System.out.printf("%s,", val.toString())));

          System.out.println("Query with named parameters performed successfully.");
        } catch (https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.BigQueryException.html | InterruptedException e) {
          System.out.println("Query not performed \n" + e.toString());
        }
      }
    }

### Python


Before trying this sample, follow the Python setup instructions in the
[BigQuery quickstart using
client libraries](https://docs.cloud.google.com/bigquery/docs/quickstarts/quickstart-client-libraries).


For more information, see the
[BigQuery Python API
reference documentation](https://docs.cloud.google.com/python/docs/reference/bigquery/latest).


To authenticate to BigQuery, set up Application Default Credentials.
For more information, see

[Set up authentication for client libraries](https://docs.cloud.google.com/bigquery/docs/authentication#client-libs).

    from google.cloud import https://docs.cloud.google.com/python/docs/reference/bigquery/latest

    # Construct a BigQuery client object.
    client = https://docs.cloud.google.com/python/docs/reference/bigquery/latest.https://docs.cloud.google.com/python/docs/reference/bigquery/latest/google.cloud.bigquery.client.Client.html()

    query = """
        SELECT word, word_count
        FROM `bigquery-public-data.samples.shakespeare`
        WHERE corpus = @corpus
        AND word_count >= @min_word_count
        ORDER BY word_count DESC;
    """
    job_config = https://docs.cloud.google.com/python/docs/reference/bigquery/latest.https://docs.cloud.google.com/python/docs/reference/bigquery/latest/google.cloud.bigquery.job.QueryJobConfig.html(
        query_parameters=[
            https://docs.cloud.google.com/python/docs/reference/bigquery/latest.https://docs.cloud.google.com/python/docs/reference/bigquery/latest/google.cloud.bigquery.query.ScalarQueryParameter.html("corpus", "STRING", "romeoandjuliet"),
            https://docs.cloud.google.com/python/docs/reference/bigquery/latest.https://docs.cloud.google.com/python/docs/reference/bigquery/latest/google.cloud.bigquery.query.ScalarQueryParameter.html("min_word_count", "INT64", 250),
        ]
    )
    results = client.https://docs.cloud.google.com/python/docs/reference/bigquery/latest/google.cloud.bigquery.client.Client.html#google_cloud_bigquery_client_Client_query_and_wait(
        query, job_config=job_config
    )  # Make an API request.

    for row in results:
        print("{}: \t{}".format(row.word, row.word_count))

### Rust

    use google_cloud_bigquery::client::BigQuery;
    use google_cloud_bigquery_v2::model::{QueryParameter, QueryParameterType, QueryParameterValue};

    pub async fn sample(project_id: &str) -> anyhow::Result<()> {
        let client = BigQuery::builder().build().await?;

        let param = QueryParameter::new()
            .set_name("state")
            .set_parameter_type(QueryParameterType::new().set_type("STRING"))
            .set_parameter_value(QueryParameterValue::new().set_value("TX"));

        let mut rows = client
            .query(
                "SELECT \
            name FROM `bigquery-public-data.usa_names.usa_1910_2013` \
            WHERE state = @state \
            LIMIT 100",
            )
            .with_project_id(project_id)
            .set_parameter_mode("NAMED")
            .set_query_parameters(vec![param])
            .set_location("US")
            .until_done()
            .await?
            .read();

        while let Some(row) = rows.next().await.transpose()? {
            let name: String = row.get("name")?;
            println!("Name: {name}");
        }
        Ok(())
    }

## What's next


To search and filter code samples for other Google Cloud products, see the
[Google Cloud sample browser](https://docs.cloud.google.com/docs/samples?product=bigquery).