Shane Wright <me@shanewright.co.uk> writes:
> SELECT
> [fields],
> [expression],
> (SELECT * FROM table2 WHERE [expression]) AS mynewfield
> FROM
> table
> GROUP BY
> [expression]
> But, it gives this error:
> ERROR: Sub-SELECT uses un-GROUPed attribute [table].[field] from outer
> query
Yeah, the code is not bright enough to figure out that this could be
considered legitimate. But try this:
SELECT [fields], myexpr, (SELECT * FROM table2 WHERE ss.myexpr) AS mynewfield
FROM (SELECT [fields], [expression] as myexpr FROM table GROUP BY myexpr) AS ss
regards, tom lane