CREATE TRIGGER trg_ins_upd_SACH ON SACH
FOR INSERT, UPDATE
AS
BEGIN
    DECLARE @MASACH CHAR(5), NHAXUATBAN VARCHAR(20)
    SELECT @MASACH = MASACH FROM INSERTED
    SELECT @NHAXUATBAN = NHAXUATBAN FROM PHATHANH WHERE MASACH = @MASACH
    IF (@MASACH = 'Giáo khoa' AND @NHAXUATBAN <> 'Giáo dục')
    BEGIN
        PRINT('Sach thuoc the loai Giao khoa chi do NXB Giao duc phat hanh')
        ROLLBACK TRANSACTION
    END
END