SQL Server 2016 introduced System-versioned Temporal Table to keep a history of data change by adding additional history table.

In the below article, You can read more about System-versioned Temporal Table and you must know all the rules before creating a System-versioned Temporal Table.

You can also enable System-versioned Temporal Table in the existing table.

Check this demonstration:

Create a table with sample data:

CREATE TABLE tbl_Employees
(
	EmpID INT PRIMARY KEY
	,EmpName VARCHAR(20)
	,EmpDepartment VARCHAR(20)
	,EmpSalary INT
)
GO
 
INSERT INTO tbl_Employees
VALUES 
(1,'Anvesh','Database',90000)
,(2,'Jenny','JAVA',65000)
,(3,'Martin','PHP',85000)
,(4,'Roy','PHP',94000)
GO

Enable System-versioned Temporal Table on this table:

ALTER TABLE tbl_Employees
SET (SYSTEM_VERSIONING = ON (HISTORY_TABLE=dbo.tbl_EmployeesHistory))
GO

You will get a below error because you must configure SYSTEM_TIME column.

Msg 13510, Level 16, State 1, Line 1
Cannot set SYSTEM_VERSIONING to ON when SYSTEM_TIME period is not defined.

Configure SYSTEM_TIME column:

ALTER TABLE tbl_Employees
ADD 
	StartTime DATETIME2 GENERATED ALWAYS AS ROW START DEFAULT GETUTCDATE()
	,EndTime DATETIME2 GENERATED ALWAYS AS ROW END DEFAULT CONVERT(DATETIME2, '9999-12-31 23:59:59.9999999') 
	,PERIOD FOR SYSTEM_TIME (StartTime, EndTime)  
GO

Now, enable System-versioned Temporal Table:

ALTER TABLE tbl_Employees
SET (SYSTEM_VERSIONING = ON (HISTORY_TABLE=dbo.tbl_EmployeesHistory))
GO