Обсуждение: Subselect returning 2 columns

Hello,

Is correct to do something like?:

SELECT row1,row2 FROM mytable
WHERE (row1,row3) IN
(SELECT row1 as p1,MAX(row3) as p2 FROM mytable
WHERE row3 <= current_date
GROUP BY row1)

I mean, I don't see documentation about subselects returning more than 
one column, but it seems to work...

Thanks,
Francesc.

Francesc Leveque <webmaster@loroadictos.com> writes:
> Is correct to do something like?:

> SELECT row1,row2 FROM mytable
> WHERE (row1,row3) IN
> (SELECT row1 as p1,MAX(row3) as p2 FROM mytable
> WHERE row3 <= current_date
> GROUP BY row1)

Sure.

> I mean, I don't see documentation about subselects returning more than 
> one column, but it seems to work...

http://www.postgresql.org/docs/7.4/static/functions-subquery.html#AEN12497
        regards, tom lane