结构体参数

使用结构体参数运行查询。

深入探索

如需查看包含此代码示例的详细文档，请参阅以下内容：

• 运行参数化查询

代码示例

Go

试用此示例之前，请按照 BigQuery 快速入门：使用客户端库中的 Go 设置说明进行操作。如需了解详情，请参阅 BigQuery Go API 参考文档。

如需向 BigQuery 进行身份验证，请设置应用默认凭据。 如需了解详情，请参阅为客户端库设置身份验证。

import (
	"context"
	"fmt"
	"io"

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

// queryWithStructParam demonstrates running a query and providing query parameters that include struct
// types.
func queryWithStructParam(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()

	type MyStruct struct {
		X int64
		Y string
	}
	q := client.Query(
		`SELECT @struct_value as s;`)
	q.Parameters = []bigquery.QueryParameter{
		{
			Name:  "struct_value",
			Value: MyStruct{X: 1, Y: "foo"},
		},
	}
	// 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.Value
		err := it.Next(&row)
		if err == iterator.Done {
			break
		}
		if err != nil {
			return err
		}
		fmt.Fprintln(w, row)
	}
	return nil
}

Java

试用此示例之前，请按照 BigQuery 快速入门：使用客户端库中的 Java 设置说明进行操作。如需了解详情，请参阅 BigQuery Java API 参考文档。

如需向 BigQuery 进行身份验证，请设置应用默认凭据。 如需了解详情，请参阅为客户端库设置身份验证。

import com.google.cloud.bigquery.BigQuery;
import com.google.cloud.bigquery.BigQueryException;
import com.google.cloud.bigquery.BigQueryOptions;
import com.google.cloud.bigquery.QueryJobConfiguration;
import com.google.cloud.bigquery.QueryParameterValue;
import com.google.cloud.bigquery.TableResult;
import java.util.HashMap;
import java.util.Map;

public class QueryWithStructsParameters {

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

  public static void queryWithStructsParameters() {
    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.
      BigQuery bigquery = BigQueryOptions.getDefaultInstance().getService();

      // Create struct
      Map<String, QueryParameterValue> struct = new HashMap<>();
      struct.put("x", QueryParameterValue.int64(1));
      struct.put("y", QueryParameterValue.string("foo"));
      QueryParameterValue recordValue = QueryParameterValue.struct(struct);

      String query = "SELECT STRUCT(@recordField) AS s";
      QueryJobConfiguration queryConfig =
          QueryJobConfiguration.newBuilder(query)
              .addNamedParameter("recordField", recordValue)
              .build();

      TableResult results = bigquery.query(queryConfig);

      results
          .iterateAll()
          .forEach(row -> row.forEach(val -> System.out.printf("%s", val.toString())));

      System.out.println("Query with struct parameter performed successfully.");
    } catch (BigQueryException | InterruptedException e) {
      System.out.println("Query not performed \n" + e.toString());
    }
  }
}

Node.js

试用此示例之前，请按照 BigQuery 快速入门：使用客户端库中的 Node.js 设置说明进行操作。如需了解详情，请参阅 BigQuery Node.js API 参考文档。

如需向 BigQuery 进行身份验证，请设置应用默认凭据。 如需了解详情，请参阅为客户端库设置身份验证。

// Run a query using struct query parameters

// Import the Google Cloud client library
const {BigQuery} = require('@google-cloud/bigquery');
const bigquery = new BigQuery();

async function queryParamsStructs() {
  // The SQL query to run
  const sqlQuery = 'SELECT @struct_value AS struct_obj;';

  const options = {
    query: sqlQuery,
    // Location must match that of the dataset(s) referenced in the query.
    location: 'US',
    params: {struct_value: {x: 1, y: 'foo'}},
  };

  // Run the query
  const [rows] = await bigquery.query(options);

  console.log('Rows:');
  rows.forEach(row => console.log(row.struct_obj.y));
}

Python

试用此示例之前，请按照 BigQuery 快速入门：使用客户端库中的 Python 设置说明进行操作。如需了解详情，请参阅 BigQuery Python API 参考文档。

如需向 BigQuery 进行身份验证，请设置应用默认凭据。 如需了解详情，请参阅为客户端库设置身份验证。

from google.cloud import bigquery

# Construct a BigQuery client object.
client = bigquery.Client()

query = "SELECT @struct_value AS s;"
job_config = bigquery.QueryJobConfig(
    query_parameters=[
        bigquery.StructQueryParameter(
            "struct_value",
            bigquery.ScalarQueryParameter("x", "INT64", 1),
            bigquery.ScalarQueryParameter("y", "STRING", "foo"),
        )
    ]
)
results = client.query_and_wait(
    query, job_config=job_config
)  # Make an API request and waits for results.

for row in results:
    print(row.s)

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。