Create TRIGGER AccountChange
ON Customer
AFTER UPDATE
AS
BEGIN
    IF(UPDATE(TotalSales))
    BEGIN
        DECLARE @TotalSales MONEY,@AccountNumber NVARCHAR(20),@TotalSalesOld MONEY,@customText1 NVARCHAR(50),@AccountTypeId int

        SET @TotalSales=(SELECT TotalSales FROM INSERTED)
        SET @TotalSalesOld=(SELECT TotalSales FROM DELETED)
        SET @AccountNumber=(SELECT AccountNumber FROM INSERTED)
        SET @AccountTypeId=(SELECT AccountTypeId FROM INSERTED)


            IF(@TotalSales BETWEEN 0 AND 5000)

                    UPDATE Customer SET AccountTypeID=8 WHERE AccountNumber=@AccountNumber

   END
END