Re: Howto sort the result of UNION (without modifying its type)?

Clemens Eisserer  Friday 08 April 2011 23:44:21
> Hi,
> 
> I have a query where I UNION several select statements which return
> IDs of type INTEGER.
> 
> This works well, if the IDs don't need to be sorted:
> > SELECT id FROM table WHERE id IN ((select id FROM table WHERE ...) UNION
> > (SELECT id  FROM table_ WHERE ....))
> 
> However I need the result the UNIONs to be sorted, so I tried the following:
> > SELECT id FROM table WHERE id IN (SELECT col0 FROM ((select id FROM table
> > WHERE ...) UNION (SELECT id  FROM table_ WHERE ....)) AS col0 ORDER BY
> > col0 OFFSET X LIMIT Y)
> 
> FEHLER:  Operator existiert nicht: integer = record
> ERROR: Operator does not exist: integer = record
> LINE 1: Select id FROM table WHERE id IN (Select col0 FROM ...
> 
> Is there any way to get the results of UNIONs sorted, without
> converting it to record?
> 
> Thanks, Clemens
> 
> PS: I know the query looks really stupid, however the queries I UNION
> are auto-generated SQL.
> I don't have much choice here to write the query more efficient :/

May you try construct like this:
SELECT i FROM (/* Your query example: */ SELECT i from v1 union select i from 
v2) as alias order by i;
?
P.S. Sorry if this message was sent twice.