Oops, that second query should be SELECT COUNT(*), id % 3 AS f1 FROM table GROUP BY f1 HAVING id % 3 <> 0; On Tue, May 13, 2008 at 3:43 PM, Nathan Thatcher <n8thatcher@xxxxxxxxx> wrote: > I am in the middle of switching a bunch of queries over from MySQL to > PostgreSQL and have hit a little snag. The following query works fine > in MySQL but raises an error in postgres: > > SELECT COUNT(*), id % 3 AS f1 FROM table GROUP BY f1 HAVING f1 <> 0; > > It seems that Postgres does not recognize the alias in the HAVING > clause. Rewriting it like this works in postgres: > > SELECT COUNT(*), id % 3 AS f1 FROM table GROUP BY f1 HAVING event_id % 3 <> 0; > > I am wondering if I am missing something because this looks like my > expression (id % 3) is getting evaluated twice when it really only > should be done once. Now, this query is obviously watered down from > what I am really doing and the expression is fairly lengthy and > complex so I would prefer to not have to evaluate it more times than > necessary. > > Is this the correct way to do this, or is there a better way / a way > to get PostgreSQL to recognize an alias in the HAVING clause? > > Thanks, > Nate >
