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

On 04/08/2011 03:44 PM, Clemens Eisserer wrote:
> 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 :/
>

does this work for you?

    select u.id from (your unions) as u order by u.id