Wei Weng writes:
> I know this is not do-able, but is there any way to simulate the
> following in Postgresql 7.1?
>
> select id from
> (select id, recv_date as date from table1
> union
> select id, send_date as date from table2) AS subtable
> order by date;
I haven't actually tried whether this does not work, but ISTM that you
could simply do
select id, recv_date as date from table1
union
select id, send_date as date from table2
order by 2;
and ignore the second column when processing the result.
--
Peter Eisentraut peter_e@gmx.net http://funkturm.homeip.net/~peter