use query result in a second query

Hello,

thanks for that suggestion, but the context of this query makes it very inefficient to do that.

the actual query looks something like this:

select a, b, c from someothertable where id = $1
UNION
select a, b, c from someothertable1 where id = $1
UNION
select a, b, c from someothertable2 where id = $1
UNION
select a, b, c from someothertable3 where id = $1

and so on with very MANY unions of some quite complex queries (the actual query I am working with is already more than 250 lines!).  The issue is that if I try to use that sub-query method, then the query takes several minutes to complete! (i need it to return in just a couple of seconds!)

therefore, I am trying to work out how I can first evaluate that 'subquery' and then use that as argument to the main query, something like:

$2 = select name from themaintable where id = $1

select a, b, c from someothertable where id = $2
UNION
select a, b, c from someothertable1 where id = $2
UNION
select a, b, c from someothertable2 where id = $2
UNION
select a, b, c from someothertable3 where id = $2

Fine, then use temprary tables. Store the result of first query to a temporary table and use this temporary table in second query. Pease refer help on temporary tables.

Note: be carefull in using temporary tables. In some database you need to delete the tempory table after use. Other wise it will remain there and finally ends up outof disk space.

ok, thanks again, but that method is also not exactly what I am looking for.

I am getting close - this is something:
-------------------------------------------------------------------------------------------------------------------
CREATE OR REPLACE FUNCTION replylist(character varying)
  RETURNS record AS
$BODY$
DECLARE
        n character varying;
      r RECORD;
BEGIN
n = name from names where id = $1;
FOR r IN select * from mytable where username = n
LOOP
RETURN r;
END LOOP;
RETURN NULL;
END;

$BODY$
  LANGUAGE 'plpgsql' VOLATILE;
-------------------------------------------------------------------------------------------------------------------

this appears to do what I need, but I am getting lost with the type definitions etc:

ERROR:  cannot assign non-composite value to a record variable
CONTEXT:  PL/pgSQL function "replylist" line 5 at assignment

What I really want to do is use REPLY QUERY, but perhaps it is not supported in the version I am using(?)

any suggestions?

Cheers.