Hi,why column "acoltest" is not found by the subselect in this select: SELECT acol + 100 as acoltest, (select max(t) from mytab where anothercol=acoltest) as col2 FROM mytab2 group by somet ??? Only columns belonging to a table can be used in a subselect??? What about "calculated" columns? Thank you
Looks like you are trying to do a correlated subquery. You can do them in both Postgres and MySQL. It needs to be done in the where clause on postgres but can be used in the select clause on MySQL and Oracle. The problem with correlated subqueries is that they are executed once for every row in the outer query, so they are usually quite a bit slower than doing a join like Sam suggested.
Scott -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
