Table exists

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 .

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

  import 
  
 ( 
  
 "context" 
  
 "errors" 
  
 "fmt" 
  
 "net/http" 
  
 "cloud.google.com/go/bigquery" 
  
 "google.golang.org/api/googleapi" 
 ) 
 // tableExists checks whether a table exists in 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 .

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

  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 .

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

  // 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 .

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

  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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Code sample

Go

Java

Node.js

Python

What's next

Table exists