Thanks to all. The problem was that, although I showed a * in the
SELECT clause, I was actually selecting fields. - I did not think that
was where the problem was so I just showed the *. The SELECT actually
selected the linkfield, but did not specify from which table and that
caused the ambiguity. Someone pointed out the problem with SELECT *
which immediately pointed to my error
Thanks a lot.

>
> SQL statement
>
> 'SELECT * ' +
> ' FROM FIRSTTABLE A, SECONDTABLE B' +
> ' WHERE B.linkfield = A.linkfield';
>
> // ' FROM FIRSTTABLE, SECONDTABLE' +
> // ' WHERE FIRSTTABLE.linkfield = SECONDTABLE.linkfield';
> (This was another attempt but getting the same answer
>
> Error Message
>
> Database Server Error: Ambiguous field name between table FIRSTTABLE
> and table SECONDTABLE LINKFIELD
>
> Any suggestions?
>