Table exists

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A function to check whether a table exists.

Code sample

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. 

import (
	"context"
	"errors"
	"fmt"
	"net/http"

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

// tableExists checks wheter a table exists on a given dataset.
func tableExists(projectID, datasetID, tableID string) error {
	// projectID := "my-project-id"
	// datasetID := "mydatasetid"
	// tableID := "mytableid"
	ctx := context.Background()

	client, err := bigquery.NewClient(ctx, projectID)
	if err != nil {
		return fmt.Errorf("bigquery.NewClient: %w", err)
	}
	defer client.Close()

	tableRef := client.Dataset(datasetID).Table(tableID)
	if _, err = tableRef.Metadata(ctx); err != nil {
		if e, ok := err.(*googleapi.Error); ok {
			if e.Code == http.StatusNotFound {
				return errors.New("dataset or table not found")
			}
		}
	}
	return nil
}

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. 

import com.google.cloud.bigquery.BigQuery;
import com.google.cloud.bigquery.BigQueryException;
import com.google.cloud.bigquery.BigQueryOptions;
import com.google.cloud.bigquery.Table;
import com.google.cloud.bigquery.TableId;

// Sample to check table exist
public class TableExists {

  public static void main(String[] args) {
    // TODO(developer): Replace these variables before running the sample.
    String datasetName = "MY_DATASET_NAME";
    String tableName = "MY_TABLE_NAME";
    tableExists(datasetName, tableName);
  }

  public static void tableExists(String datasetName, String tableName) {
    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();

      Table table = bigquery.getTable(TableId.of(datasetName, tableName));
      if (table != null
          && table
              .exists()) { // table will be null if it is not found and setThrowNotFound is not set
        // to `true`
        System.out.println("Table already exist");
      } else {
        System.out.println("Table not found");
      }
    } catch (BigQueryException e) {
      System.out.println("Table not found. \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. 

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

async function tableExists() {
  // Checks whether table named "my_table" in "my_dataset" exists.

  /**
   * TODO(developer): Uncomment the following lines before running the sample
   */
  // const datasetId = "my_dataset";
  // const tableId = "my_table";

  // Retrieve table reference
  const dataset = bigquery.dataset(datasetId);

  try {
    await dataset.table(tableId).get();
    console.log(`Table ${tableId} exists.`);
  } catch (e) {
    console.log(e.message);
  }
}
tableExists();

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. 

from google.cloud import bigquery
from google.cloud.exceptions import NotFound

client = bigquery.Client()

# TODO(developer): Set table_id to the ID of the table to determine existence.
# table_id = "your-project.your_dataset.your_table"

try:
    client.get_table(table_id)  # Make an API request.
    print("Table {} already exists.".format(table_id))
except NotFound:
    print("Table {} is not found.".format(table_id))

What's next

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