Using set operations (subqueries) with cursors

Question

If would need the following statement fe.:
select * from A where attr1 in (select attr3 from B where ...);
and the substatement select att3... is very complex and i want to do it only once. Is it possible to use it as a cursor:
open C0 for select attr3 from B where ...;
and do something like that, in a couple of following statements?
select * from A where attr1 in (C0);
select * from A1 where attr1 in (C0);
.

Answer 1

If you're using 9i DB then you can use the subquery factoring clause, viz:
WITH c0 AS (SELECT attr3 FROM b WHERE...)
SELECT * FROM a
WHERE  a.attr1 IN (select attr3 from c0)
UNION ALL
SELECT * FROM a1
WHERE  a1.attr1 IN (select attr3 from c0)I agree this is a little forced, but I thought you were looking to use the sub-query several times in the same SQL statement rather than multiple statements. I just didn't want to waste the typing :P
Cheers, APC