--- In firebird-support@yahoogroups.com, "unordained"
<unordained_00@...> wrote:

>
> >> select a.*, (select count(*) from a1 where a1.b_id = b.id) as F1

from tb a where (select count

> (*) from a1 where a1.b_id = b.id) = 100; [Alan]
>
> or if you're using FB2, something like:
>
> select z.* from
> (select a.*, (select count(*) from a1 where a1.b_id = b.id) as F1

from tb a) z

> where z.F1 = 100;
>
> or if you're using FB2.1, you could also try:
>
> with z (select a.*, (select count(*) from a1 where a1.b_id = b.id)

as F1 from tb a)

> select z.* from z where z.F1 = 100;
>
> As far as I know, there's no performance difference between any of

these options? (incl. Alan's?)

>
> - Philip
>

Thank you very much, that's great. I didn't know about table alias
before.