@@ERROR
Returns the error number for the last Transact-SQL statement executed.


USE pubs
GO
DECLARE @del_error int, @ins_error int
-- Start a transaction.
BEGIN TRAN

-- Execute the DELETE statement.
DELETE authors
WHERE au_id = '409-56-7088'

-- Set a variable to the error value for
-- the DELETE statement.
SELECT @del_error = @@ERROR

-- Execute the INSERT statement.
INSERT authors
VALUES('409-56-7008', 'Bennet', 'Abraham', '415 658-9932',
'6223 Bateman St.', 'Berkeley', 'CA', '94705', 1)
-- Set a variable to the error value for
-- the INSERT statement.
SELECT @ins_error = @@ERROR

-- Test the error values.
IF @del_error = 0 AND @ins_error = 0
BEGIN
-- Success. Commit the transaction.
PRINT "The author information has been replaced"
COMMIT TRAN
END
ELSE
BEGIN
-- An error occurred. Indicate which operation(s) failed
-- and roll back the transaction.
IF @del_error <> 0
PRINT "An error occurred during execution of the DELETE
statement."

IF @ins_error <> 0
PRINT "An error occurred during execution of the INSERT
statement."

ROLLBACK TRAN
END
GO


PS
А GreenSunrise прав, документацию надо читать