Subselect Question - Mailing list pgsql-general

Hi,

when creating a query with a subselect

SELECT name, (SELECT max(pop) FROM cities WHERE cities.state = states.name) AS max_pop
    FROM states;

then it is not possible to sort after max_pop or use max_pop in a function or a CASE.

am I dont anything wrong or is this meant to be the case?

Thanks
Alex