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1. 
CREATE TRIGGER TG_CAU01 ON CTPNHAP
FOR INSERT, UPDATE
AS
IF(SELECT SUM(CTPNHAP.SLNhap)
	FROM CTPNHAP JOIN INSERTED ON CTPNHAP.MAVTu = INSERTED.MaVTu)
	>
	(SELECT SUM(SLDat)
		FROM CTDONDH JOIN INSERTED ON CTDONDH.MaVTu = INSERTED.MaVTu)
BEGIN
	PRINT(N'K duoc lon hon')
	ROLLBACK TRAN
END

3. 
CREATE TRIGGER TG_CAU03 ON TONKHO
FOR INSERT, UPDATE
AS
	UPDATE TONKHO SET SLCUOI = (SELECT TONKHO.SLDAU + TONKHO.TongSLN - TONKHO.TongSLX)
	FROM TONKHO JOIN INSERTED ON TONKHO.MaVTu = INSERTED.MaVTu AND TONKHO.NAMTHANG = INSERTED.NAMTHANG)

BEGIN
END

2. 
CREATE TRIGGER TG_XoaCTDH
ON CTHD
FOR DELETE
AS
	UPDATE MATHANG SET SoTon = SoTon + SL 
	FROM DELETED
	WHERE MATHANG.MAMH = DELETED.MAMH

CREATE TRIGGER TG_SuatCTHD ON CTHD
FOR UPDATE AS
	DECLARE @D INT
	SELECT @D = COUNT(*)
	FROM MATHANG a, DELETED b, INSERTED c
	WHERE a.MaMH = b.MaMH AND a.MaMH = c.MaMH
	AND SoTon + b.SL + c.SL < 0
	IF(@D > 0)
		BEGIN
			PRINT N'Không đủ hàng để bán'
			ROLLBACK TRAN
			RETURN
		END
-----------
UPDATE MatHang SET SoTon = SoTon + b.SL - c.SL
FROM MatHang a, DELETED b, INSERTED c
WHERE a.MaMH = b.MaMH AND a.MaMH = c.MaMH