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
