On 9 February 2016 at 14:53, Tom Lane <tgl@xxxxxxxxxxxxx> wrote: > SELECT COALESCE((SELECT 'Yes' FROM gwtest WHERE id=4), 'No') AS valid; > > There's no null visible anywhere in that. I suppose that if there's > no row with id=4, there would be a null at runtime, Well yes, that was the whole point. > but that's not > going to make any difference for parse-time determination of what > type the COALESCE() will return. But when the gwtest subquery _does_ return a value it works, so the problem can't be parse-time determination, can it? Geoff -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
