Query data with commit timestamp

Query data from a table containing a commit TIMESTAMP column.

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

Code sample

C++

To learn how to install and use the client library for Spanner, see Spanner client libraries .

To authenticate to Spanner, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .

  void 
  
 QueryDataWithTimestamp 
 ( 
 google 
 :: 
 cloud 
 :: 
 spanner 
 :: 
 Client 
  
 client 
 ) 
  
 { 
  
 namespace 
  
 spanner 
  
 = 
  
 :: 
 google 
 :: 
 cloud 
 :: 
 spanner 
 ; 
  
 spanner 
 :: 
 SqlStatement 
  
 select 
 ( 
  
 "SELECT SingerId, AlbumId, MarketingBudget, LastUpdateTime" 
  
 "  FROM Albums" 
  
 " ORDER BY LastUpdateTime DESC" 
 ); 
  
 using 
  
 RowType 
  
 = 
  
 std 
 :: 
 tuple<std 
 :: 
 int64_t 
 , 
  
 std 
 :: 
 int64_t 
 , 
  
 absl 
 :: 
 optional<std 
 :: 
 int64_t 
> , 
  
 absl 
 :: 
 optional<spanner 
 :: 
 Timestamp 
>> ; 
  
 auto 
  
 rows 
  
 = 
  
 client 
 . 
 ExecuteQuery 
 ( 
 std 
 :: 
 move 
 ( 
 select 
 )); 
  
 for 
  
 ( 
 auto 
&  
 row 
  
 : 
  
 spanner 
 :: 
 StreamOf<RowType> 
 ( 
 rows 
 )) 
  
 { 
  
 if 
  
 ( 
 ! 
 row 
 ) 
  
 throw 
  
 std 
 :: 
 move 
 ( 
 row 
 ). 
 status 
 (); 
  
 std 
 :: 
 cout 
 << 
 std 
 :: 
 get<0> 
 ( 
 * 
 row 
 ) 
 << 
 " " 
 << 
 std 
 :: 
 get<1> 
 ( 
 * 
 row 
 ); 
  
 auto 
  
 marketing_budget 
  
 = 
  
 std 
 :: 
 get<2> 
 ( 
 * 
 row 
 ); 
  
 if 
  
 ( 
 ! 
 marketing_budget 
 ) 
  
 { 
  
 std 
 :: 
 cout 
 << 
 " NULL" 
 ; 
  
 } 
  
 else 
  
 { 
  
 std 
 :: 
 cout 
 << 
 ' ' 
 << 
 * 
 marketing_budget 
 ; 
  
 } 
  
 auto 
  
 last_update_time 
  
 = 
  
 std 
 :: 
 get<3> 
 ( 
 * 
 row 
 ); 
  
 if 
  
 ( 
 ! 
 last_update_time 
 ) 
  
 { 
  
 std 
 :: 
 cout 
 << 
 " NULL" 
 ; 
  
 } 
  
 else 
  
 { 
  
 std 
 :: 
 cout 
 << 
 ' ' 
 << 
 * 
 last_update_time 
 ; 
  
 } 
  
 std 
 :: 
 cout 
 << 
 " 
 \n 
 " 
 ; 
  
 } 
 }

C#

To learn how to install and use the client library for Spanner, see Spanner client libraries .

To authenticate to Spanner, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .

  using 
  
  Google.Cloud.Spanner.Data 
 
 ; 
 using 
  
 System 
 ; 
 using 
  
 System.Collections.Generic 
 ; 
 using 
  
 System.Threading.Tasks 
 ; 
 public 
  
 class 
  
 QueryDataWithTimestampColumnAsyncSample 
 { 
  
 public 
  
 class 
  
 Album 
  
 { 
  
 public 
  
 int 
  
 SingerId 
  
 { 
  
 get 
 ; 
  
 set 
 ; 
  
 } 
  
 public 
  
 int 
  
 AlbumId 
  
 { 
  
 get 
 ; 
  
 set 
 ; 
  
 } 
  
 public 
  
 DateTime 
 ? 
  
 LastUpdateTime 
  
 { 
  
 get 
 ; 
  
 set 
 ; 
  
 } 
  
 public 
  
 long? 
  
 MarketingBudget 
  
 { 
  
 get 
 ; 
  
 set 
 ; 
  
 } 
  
 } 
  
 public 
  
 async 
  
 Task<List<Album> 
>  
 QueryDataWithTimestampColumnAsync 
 ( 
 string 
  
 projectId 
 , 
  
 string 
  
 instanceId 
 , 
  
 string 
  
 databaseId 
 ) 
  
 { 
  
 string 
  
 connectionString 
  
 = 
  
 $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}" 
 ; 
  
 using 
  
 var 
  
 connection 
  
 = 
  
 new 
  
  SpannerConnection 
 
 ( 
 connectionString 
 ); 
  
 using 
  
 var 
  
 cmd 
  
 = 
  
 connection 
 . 
  CreateSelectCommand 
 
 ( 
 "SELECT SingerId, AlbumId, MarketingBudget, LastUpdateTime FROM Albums ORDER BY LastUpdateTime DESC" 
 ); 
  
 var 
  
 albums 
  
 = 
  
 new 
  
 List<Album> 
 (); 
  
 using 
  
 var 
  
 reader 
  
 = 
  
 await 
  
 cmd 
 . 
  ExecuteReaderAsync 
 
 (); 
  
 while 
  
 ( 
 await 
  
 reader 
 . 
  ReadAsync 
 
 ()) 
  
 { 
  
 albums 
 . 
 Add 
 ( 
 new 
  
 Album 
  
 { 
  
 SingerId 
  
 = 
  
 reader 
 . 
 GetFieldValue<int> 
 ( 
 "SingerId" 
 ), 
  
 AlbumId 
  
 = 
  
 reader 
 . 
 GetFieldValue<int> 
 ( 
 "AlbumId" 
 ), 
  
 LastUpdateTime 
  
 = 
  
 reader 
 . 
  IsDBNull 
 
 ( 
 reader 
 . 
  GetOrdinal 
 
 ( 
 "LastUpdateTime" 
 )) 
  
 ? 
  
 ( 
 DateTime 
 ? 
 ) 
 null 
  
 : 
  
 reader 
 . 
 GetFieldValue<DateTime> 
 ( 
 "LastUpdateTime" 
 ), 
  
 MarketingBudget 
  
 = 
  
 reader 
 . 
  IsDBNull 
 
 ( 
 reader 
 . 
  GetOrdinal 
 
 ( 
 "MarketingBudget" 
 )) 
  
 ? 
  
 0 
  
 : 
  
 reader 
 . 
 GetFieldValue<long> 
 ( 
 "MarketingBudget" 
 ) 
  
 }); 
  
 } 
  
 return 
  
 albums 
 ; 
  
 } 
 }

Go

To learn how to install and use the client library for Spanner, see Spanner client libraries .

To authenticate to Spanner, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .

  import 
  
 ( 
  
 "context" 
  
 "fmt" 
  
 "io" 
  
 "strconv" 
  
 "cloud.google.com/go/spanner" 
  
 "google.golang.org/api/iterator" 
 ) 
 func 
  
 queryWithTimestamp 
 ( 
 w 
  
 io 
 . 
 Writer 
 , 
  
 db 
  
 string 
 ) 
  
 error 
  
 { 
  
 ctx 
  
 := 
  
 context 
 . 
 Background 
 () 
  
 client 
 , 
  
 err 
  
 := 
  
 spanner 
 . 
 NewClient 
 ( 
 ctx 
 , 
  
 db 
 ) 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 return 
  
 err 
  
 } 
  
 defer 
  
 client 
 . 
 Close 
 () 
  
 stmt 
  
 := 
  
 spanner 
 . 
  Statement 
 
 { 
  
 SQL 
 : 
  
 `SELECT SingerId, AlbumId, MarketingBudget, LastUpdateTime 
 FROM Albums ORDER BY LastUpdateTime DESC` 
 } 
  
 iter 
  
 := 
  
 client 
 . 
  Single 
 
 (). 
 Query 
 ( 
 ctx 
 , 
  
 stmt 
 ) 
  
 defer 
  
 iter 
 . 
 Stop 
 () 
  
 for 
  
 { 
  
 row 
 , 
  
 err 
  
 := 
  
 iter 
 . 
 Next 
 () 
  
 if 
  
 err 
  
 == 
  
 iterator 
 . 
 Done 
  
 { 
  
 return 
  
 nil 
  
 } 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 return 
  
 err 
  
 } 
  
 var 
  
 singerID 
 , 
  
 albumID 
  
 int64 
  
 var 
  
 marketingBudget 
  
 spanner 
 . 
  NullInt64 
 
  
 var 
  
 lastUpdateTime 
  
 spanner 
 . 
  NullTime 
 
  
 if 
  
 err 
  
 := 
  
 row 
 . 
  ColumnByName 
 
 ( 
 "SingerId" 
 , 
  
& singerID 
 ); 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 return 
  
 err 
  
 } 
  
 if 
  
 err 
  
 := 
  
 row 
 . 
  ColumnByName 
 
 ( 
 "AlbumId" 
 , 
  
& albumID 
 ); 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 return 
  
 err 
  
 } 
  
 if 
  
 err 
  
 := 
  
 row 
 . 
  ColumnByName 
 
 ( 
 "MarketingBudget" 
 , 
  
& marketingBudget 
 ); 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 return 
  
 err 
  
 } 
  
 budget 
  
 := 
  
 "NULL" 
  
 if 
  
 marketingBudget 
 . 
 Valid 
  
 { 
  
 budget 
  
 = 
  
 strconv 
 . 
 FormatInt 
 ( 
 marketingBudget 
 . 
  Int64 
 
 , 
  
 10 
 ) 
  
 } 
  
 if 
  
 err 
  
 := 
  
 row 
 . 
  ColumnByName 
 
 ( 
 "LastUpdateTime" 
 , 
  
& lastUpdateTime 
 ); 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 return 
  
 err 
  
 } 
  
 timestamp 
  
 := 
  
 "NULL" 
  
 if 
  
 lastUpdateTime 
 . 
 Valid 
  
 { 
  
 timestamp 
  
 = 
  
 lastUpdateTime 
 . 
 String 
 () 
  
 } 
  
 fmt 
 . 
 Fprintf 
 ( 
 w 
 , 
  
 "%d %d %s %s\n" 
 , 
  
 singerID 
 , 
  
 albumID 
 , 
  
 budget 
 , 
  
 timestamp 
 ) 
  
 } 
 }

Java

To learn how to install and use the client library for Spanner, see Spanner client libraries .

To authenticate to Spanner, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .

  static 
  
 void 
  
 queryMarketingBudgetWithTimestamp 
 ( 
 DatabaseClient 
  
 dbClient 
 ) 
  
 { 
  
 // Rows without an explicit value for MarketingBudget will have a MarketingBudget equal to 
  
 // null. A try-with-resource block is used to automatically release resources held by 
  
 // ResultSet. 
  
 try 
  
 ( 
 ResultSet 
  
 resultSet 
  
 = 
  
 dbClient 
  
 . 
 singleUse 
 () 
  
 . 
 executeQuery 
 ( 
  
 Statement 
 . 
 of 
 ( 
  
 "SELECT SingerId, AlbumId, MarketingBudget, LastUpdateTime FROM Albums" 
  
 + 
  
 " ORDER BY LastUpdateTime DESC" 
 ))) 
  
 { 
  
 while 
  
 ( 
 resultSet 
 . 
 next 
 ()) 
  
 { 
  
 System 
 . 
 out 
 . 
 printf 
 ( 
  
 "%d %d %s %s\n" 
 , 
  
 resultSet 
 . 
 getLong 
 ( 
 "SingerId" 
 ), 
  
 resultSet 
 . 
 getLong 
 ( 
 "AlbumId" 
 ), 
  
 // We check that the value is non null. ResultSet getters can only be used to retrieve 
  
 // non null values. 
  
 resultSet 
 . 
 isNull 
 ( 
 "MarketingBudget" 
 ) 
  
 ? 
  
 "NULL" 
  
 : 
  
 resultSet 
 . 
 getLong 
 ( 
 "MarketingBudget" 
 ), 
  
 resultSet 
 . 
 isNull 
 ( 
 "LastUpdateTime" 
 ) 
  
 ? 
  
 "NULL" 
  
 : 
  
 resultSet 
 . 
 getTimestamp 
 ( 
 "LastUpdateTime" 
 )); 
  
 } 
  
 } 
 }

Node.js

To learn how to install and use the client library for Spanner, see Spanner client libraries .

To authenticate to Spanner, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .

  // ... 
 // Imports the Google Cloud client library 
 const 
  
 { 
 Spanner 
 } 
  
 = 
  
 require 
 ( 
 ' @google-cloud/spanner 
' 
 ); 
 /** 
 * TODO(developer): Uncomment the following lines before running the sample. 
 */ 
 // const projectId = 'my-project-id'; 
 // const instanceId = 'my-instance'; 
 // const databaseId = 'my-database'; 
 // Creates a client 
 const 
  
 spanner 
  
 = 
  
 new 
  
  Spanner 
 
 ({ 
  
 projectId 
 : 
  
 projectId 
 , 
 }); 
 // Gets a reference to a Cloud Spanner instance and database 
 const 
  
 instance 
  
 = 
  
 spanner 
 . 
 instance 
 ( 
 instanceId 
 ); 
 const 
  
 database 
  
 = 
  
 instance 
 . 
 database 
 ( 
 databaseId 
 ); 
 const 
  
 query 
  
 = 
  
 { 
  
 sql 
 : 
  
 `SELECT SingerId, AlbumId, MarketingBudget, LastUpdateTime 
 FROM Albums ORDER BY LastUpdateTime DESC` 
 , 
 }; 
 // Queries rows from the Albums table 
 try 
  
 { 
  
 const 
  
 [ 
 rows 
 ] 
  
 = 
  
 await 
  
 database 
 . 
 run 
 ( 
 query 
 ); 
  
 rows 
 . 
 forEach 
 ( 
 row 
  
 = 
>  
 { 
  
 const 
  
 json 
  
 = 
  
 row 
 . 
 toJSON 
 (); 
  
 console 
 . 
 log 
 ( 
  
 `SingerId: 
 ${ 
 json 
 . 
 SingerId 
 } 
 , AlbumId: 
 ${ 
  
 json 
 . 
 AlbumId 
  
 } 
 , MarketingBudget: 
 ${ 
  
 json 
 . 
 MarketingBudget 
  
 ? 
  
 json 
 . 
 MarketingBudget 
  
 : 
  
 null 
  
 } 
 , LastUpdateTime: 
 ${ 
 json 
 . 
 LastUpdateTime 
 } 
 ` 
 , 
  
 ); 
  
 }); 
 } 
  
 catch 
  
 ( 
 err 
 ) 
  
 { 
  
 console 
 . 
 error 
 ( 
 'ERROR:' 
 , 
  
 err 
 ); 
 } 
  
 finally 
  
 { 
  
 // Close the database when finished 
  
 database 
 . 
 close 
 (); 
 }

PHP

To learn how to install and use the client library for Spanner, see Spanner client libraries .

To authenticate to Spanner, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .

  use Google\Cloud\Spanner\SpannerClient; 
 /** 
 * Queries sample data from a database with a commit timestamp column. 
 * 
 * This sample uses the `MarketingBudget` column. You can add the column 
 * by running the `add_column` sample or by running this DDL statement against 
 * your database: 
 * 
 *      ALTER TABLE Albums ADD COLUMN MarketingBudget INT64 
 * 
 * This sample also uses the 'LastUpdateTime' commit timestamp column. You can 
 * add the column by running the `add_timestamp_column` sample or by running 
 * this DDL statement against your database: 
 * 
 * 		ALTER TABLE Albums ADD COLUMN LastUpdateTime TIMESTAMP OPTIONS (allow_commit_timestamp=true) 
 * 
 * Example: 
 * ``` 
 * query_data_with_timestamp_column($instanceId, $databaseId); 
 * ``` 
 * 
 * @param string $instanceId The Spanner instance ID. 
 * @param string $databaseId The Spanner database ID. 
 */ 
 function query_data_with_timestamp_column(string $instanceId, string $databaseId): void 
 { 
 $spanner = new SpannerClient(); 
 $instance = $spanner->instance($instanceId); 
 $database = $instance->database($databaseId); 
 $results = $database->execute( 
 'SELECT SingerId, AlbumId, MarketingBudget, LastUpdateTime ' . 
 ' FROM Albums ORDER BY LastUpdateTime DESC' 
 ); 
 foreach ($results as $row) { 
 if ($row['MarketingBudget'] == null) { 
 $row['MarketingBudget'] = 'NULL'; 
 } 
 if ($row['LastUpdateTime'] == null) { 
 $row['LastUpdateTime'] = 'NULL'; 
 } 
 printf('SingerId: %s, AlbumId: %s, MarketingBudget: %s, LastUpdateTime: %s' . PHP_EOL, 
 $row['SingerId'], $row['AlbumId'], $row['MarketingBudget'], $row['LastUpdateTime']); 
 } 
 }

Python

To learn how to install and use the client library for Spanner, see Spanner client libraries .

To authenticate to Spanner, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .

  def 
  
 query_data_with_timestamp 
 ( 
 instance_id 
 , 
 database_id 
 ): 
  
 """Queries sample data from the database using SQL. 
 This updates the `LastUpdateTime` column which must be created before 
 running this sample. You can add the column by running the 
 `add_timestamp_column` sample or by running this DDL statement 
 against your database: 
 ALTER TABLE Performances ADD COLUMN LastUpdateTime TIMESTAMP 
 OPTIONS (allow_commit_timestamp=true) 
 """ 
 spanner_client 
 = 
 spanner 
 . 
 Client 
 () 
 instance 
 = 
 spanner_client 
 . 
 instance 
 ( 
 instance_id 
 ) 
 database 
 = 
 instance 
 . 
 database 
 ( 
 database_id 
 ) 
 with 
 database 
 . 
 snapshot 
 () 
 as 
 snapshot 
 : 
 results 
 = 
 snapshot 
 . 
 execute_sql 
 ( 
 "SELECT SingerId, AlbumId, MarketingBudget FROM Albums " 
 "ORDER BY LastUpdateTime DESC" 
 ) 
 for 
 row 
 in 
 results 
 : 
 print 
 ( 
 "SingerId: 
 {} 
 , AlbumId: 
 {} 
 , MarketingBudget: 
 {} 
 " 
 . 
 format 
 ( 
 * 
 row 
 ))

Ruby

To learn how to install and use the client library for Spanner, see Spanner client libraries .

To authenticate to Spanner, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .

  # project_id  = "Your Google Cloud project ID" 
 # instance_id = "Your Spanner instance ID" 
 # database_id = "Your Spanner database ID" 
 require 
  
 "google/cloud/spanner" 
 spanner 
  
 = 
  
 Google 
 :: 
 Cloud 
 :: 
  Spanner 
 
 . 
 new 
  
 project 
 : 
  
 project_id 
 client 
  
 = 
  
 spanner 
 . 
  client 
 
  
 instance_id 
 , 
  
 database_id 
 client 
 . 
 execute 
 ( 
 "SELECT SingerId, AlbumId, MarketingBudget, LastUpdateTime 
 FROM Albums ORDER BY LastUpdateTime DESC" 
 ) 
 . 
 rows 
 . 
  each 
 
  
 do 
  
 | 
 row 
 | 
  
 puts 
  
 " 
 #{ 
 row 
 [ 
 :SingerId 
 ] 
 } 
  
 #{ 
 row 
 [ 
 :AlbumId 
 ] 
 } 
  
 #{ 
 row 
 [ 
 :MarketingBudget 
 ] 
 } 
  
 #{ 
 row 
 [ 
 :LastUpdateTime 
 ] 
 } 
 " 
 end

What's next

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Query data with commit timestamp Stay organized with collections Save and categorize content based on your preferences.

Explore further

Code sample

C++

C#

Go

Java

Node.js

PHP

Python

Ruby

What's next

Query data with commit timestamp