Blocking query in SSMS(SQL Server Management Studio)

Question

I am a Fresher in writing queries.
I wrote following a query to block the A/P invoice, if price added in A/P invoice and the Price in Price list is different.
and this invoice should not be able to add by users other than UserSign = 5,6.
IF (@transaction_type='A' OR @transaction_type = 'U') AND @OBJECT_TYPE='18'
BEGIN
    If EXISTS(SELECT T1.ItemCode,
            T1.Price AS Inv_Price,
            T2.U_ListPrice AS Listed_Price
    FROM OPCH AS T0 
        INNER JOIN
        PCH1 AS T1 ON
         T0.DocEntry = T1.DocEntry
        LEFT OUTER JOIN    
        dbo.[@PRICELISTS] AS T2 ON
         T0.CardCode = T2.U_BPCode AND
         T1.ItemCode = T2.U_ItemNo
    WHERE
        (T0.UserSign <> 6) AND
        (T0.UserSign <> 5) AND
        (T1.DocEntry = @list_of_cols_val_tab_del) AND
        (T1.Price <> T2.U_ListPrice)
        (T2.U_ListCurrency = T0.DocCur)
BEGIN
SET @error = 123 --1234567991234567918
SET @error_message = 'Deviation in price'
END
After executing, still everyone can add the A/P invoice with price difference.
Please look at the above code and help me to find out my fault to make it correct.
Is there any need to add some condition in where clause?
Regards,
Hitul Varia

Answer 1

Hi,
Try this:
IF (@transaction_type='A' OR @transaction_type = 'U') AND @OBJECT_TYPE='18'
BEGIN
    If EXISTS(SELECT T0.docentry
    FROM OPCH  T0 
        INNER JOIN
        PCH1  T1 ON
         T0.DocEntry = T1.DocEntry
        LEFT OUTER JOIN    
        dbo.[@PRICELISTS]  T2 ON
         T0.CardCode = T2.U_BPCode AND
         T1.ItemCode = T2.U_ItemNo
    WHERE
        (T0.UserSign <> 6 OR
        T0.UserSign <> 5) AND
        T0.DocEntry = @list_of_cols_val_tab_del AND
        T1.Price <> T2.U_ListPrice and
        T2.U_ListCurrency = T0.DocCur)
BEGIN
SET @error = 123 --1234567991234567918
SET @error_message = 'Deviation in price'
END
Thanks & Regards,
Nagarajan