Returns the number of rows affected by the last statement. It will let you to do a checking on the record you updated.
If the number of rows is more than 2 billion, use ROWCOUNT_BIG.
Example
USE DB2008;
GO
UPDATE User
SET JobTitle = 'Manager'
WHERE UserID = 'u10021'
IF @@ROWCOUNT = 0
PRINT 'Warning: No rows were updated';
GO
