Re: Why does this SQL work?
| От | Victor Yegorov |
|---|---|
| Тема | Re: Why does this SQL work? |
| Дата | |
| Msg-id | CAGnEbojvNhei9qGhB4GTbgytAOhkD6rKZK+a=gS22qsz4DameQ@mail.gmail.com обсуждение исходный текст |
| Ответ на | Why does this SQL work? (Anil Menon <gakmenon@gmail.com>) |
| Ответы |
Re: Why does this SQL work?
|
| Список | pgsql-general |
2015-05-11 19:26 GMT+03:00 Anil Menon <gakmenon@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
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