>Hi,
>
>I am getting error "invalid subquery" when using the following SQL Select:
>
>

>select TABLE1.* FROM TABLE1 WHERE ID_FLD IN (select TABLE2.ID_FLD, SUM(
> TABLE2.QUANTITY)  as USED_QUANTITY FROM TABLE2 GROUP BY TABLE2.ID_FLD) 
>

>
>The only thing that I see that could be causing this error is GROUP BY. Is this correct?

You need to group by in the inner select.

But what exactly do you want to achieve here?

select TABLE1.*, SumInfo.Used_Quantity FROM TABLE1 
INNER JOIN (select TABLE2.ID_FLD, SUM(
 TABLE2.QUANTITY)  as USED_QUANTITY FROM TABLE2 GROUP BY TABLE2.ID_FLD) SumInfo 
on Table1.ID_Fld = SumInfo.ID_Fld

If you want to check FLD IN (SubSelect), then SubSelect MUST return only one field.