Thank you very much - looks like I will have to prefix all cols. Regards AK
On Tue, May 12, 2015 at 3:05 AM, Victor Yegorov <vyego...@gmail.com> wrote: > 2015-05-11 19:26 GMT+03:00 Anil Menon <gakme...@gmail.com>: > >> manualscan=> select count(*) From public.msgtxt where msgid in (select >> msgid From ver736.courier where org_id=3); >> count >> ------- >> 10225 >> (1 row) >> >> Please note, there is no msgid col in courier table. Which brings the >> question why does this SQL work? An "select msgid From courier where >> org_id=3" by itself gives error column "msgid" does not exist. >> > > Because you can reference both, inner and outer columns from the inner > query. > Here you're most likely referring to the outer `msgid` in the subquery. > > That's why it is always a good idea to prefix all your columns with tables > aliases. > > > -- > Victor Y. Yegorov >
