>Hi,
>
>I am running into a problem where the error message is:
>

>Only one expression can be specified in the select list when the
>subquery is not introduced with EXISTS
>

>
>The SQL Select is as follows:
>

>select Table1.Field1 from Table1 where Tabel1.Field1 in (select Table2.Field1, Table2.Field2 from Table2 where 
>Table2.Field2 in (select Table3.Field2 from Table3))
>

>
>That is, in the above SQL Select there are two IN clauses.
>
>Does the error mean that I have to change the second IN with EXISTS? Or both IN have to be change to EXISTS?
>
>TIA


In your example EXISTS() should perform much faster than IN(). So if the tables are large you might consider:

select Table1.Field1 from Table1 
    where EXISTS(select null from table2 join table3 on table2.field2 = table3.field2 and table2.field1 = table1.field1)

Exists will stop looking once it found a match, and the inner join of table2 and table3 automatically filters records that exist in both tables.