Microsoft SQL Server Temporal Tables CREATE Temporal Tables


Example

CREATE TABLE dbo.Employee   
(    
  [EmployeeID] int NOT NULL PRIMARY KEY CLUSTERED   
  , [Name] nvarchar(100) NOT NULL  
  , [Position] varchar(100) NOT NULL   
  , [Department] varchar(100) NOT NULL  
  , [Address] nvarchar(1024) NOT NULL  
  , [AnnualSalary] decimal (10,2) NOT NULL  
  , [ValidFrom] datetime2 (2) GENERATED ALWAYS AS ROW START  
  , [ValidTo] datetime2 (2) GENERATED ALWAYS AS ROW END  
  , PERIOD FOR SYSTEM_TIME (ValidFrom, ValidTo)  
 )    
 WITH (SYSTEM_VERSIONING = ON (HISTORY_TABLE = dbo.EmployeeHistory));  

INSERTS: On an INSERT, the system sets the value for the ValidFrom column to the begin time of the current transaction (in the UTC time zone) based on the system clock and assigns the value for the ValidTo column to the maximum value of 9999-12-31. This marks the row as open.

UPDATES: On an UPDATE, the system stores the previous value of the row in the history table and sets the value for the ValidTo column to the begin time of the current transaction (in the UTC time zone) based on the system clock. This marks the row as closed, with a period recorded for which the row was valid. In the current table, the row is updated with its new value and the system sets the value for the ValidFrom column to the begin time for the transaction (in the UTC time zone) based on the system clock. The value for the updated row in the current table for the ValidTo column remains the maximum value of 9999-12-31.

DELETES: On a DELETE, the system stores the previous value of the row in the history table and sets the value for the ValidTo column to the begin time of the current transaction (in the UTC time zone) based on the system clock. This marks the row as closed, with a period recorded for which the previous row was valid. In the current table, the row is removed. Queries of the current table will not return this row. Only queries that deal with history data return data for which a row is closed.

MERGE: On a MERGE, the operation behaves exactly as if up to three statements (an INSERT, an UPDATE, and/or a DELETE) executed, depending on what is specified as actions in the MERGE statement.

Tip : The times recorded in the system datetime2 columns are based on the begin time of the transaction itself. For example, all rows inserted within a single transaction will have the same UTC time recorded in the column corresponding to the start of the SYSTEM_TIME period.