Dear Sir,

     I had used a statement like this:
 select * from tab1,tab2 where tab1.id = tab2.p_id and tab1.id=
(select tab3.id from tab3 where id=:par)

Use then reserved SQL word <IN> something like

select * from tab1,tab2 where tab1.id = tab2.p_id and
    in (select tab3.id from tab3 where id=:par and tab1.id = tab3.id)

or this

 select * from tab1,tab2 where in
    (select
        tab3.id
    from
        tab3
    where in
        id=:par and
        tab1.id =
        tab3.id and
        tab1.id = tab2.p_id)

I don't know if the syntax is correct but i know you can use the <IN> word.