CREATE procedure timsoluongmonan
@mamonan NVARCHAR(20),
@ngaydatban DATETIME
AS
BEGIN TRAN
	------- kiem tra mon an
	IF NOT EXISTS (SELECT tenmonan=@mamonan FROM dbo.MonAn)
	BEGIN
		ROLLBACK TRAN
	END

	------- kiem tra ngay
	IF NOT EXISTS (SELECT ngaydatban FROM dbo.NhatKyDatBan WHERE ngaydatban=@ngaydatban)
	BEGIN
		ROLLBACK TRAN
	END

	------ \
	SELECT SUM(sl)
	FROM ChiTietDatBan, NhatKyDatBan, MonAn
	WHERE ChiTietDatBan.mankdb = NhatKyDatBan.mankdb AND NhatKyDatban.ngaydatban = @ngaydatban

COMMIT TRAN
GO