On Friday 31 March 2006 08:30, chris smith wrote: > On 3/31/06, Andrus <eetasoft@xxxxxxxxx> wrote: > > >> In real application I have long expression instead of 123 and do'nt > > >> want repeat this expression in HAVING clause. > > > > > > You have to repeat the expression. "AS" changes the output name, it > > > can't be used either in the where clause or any other limiting factor > > > like 'having': > > > > Doc about HAVING condition says: > > > > Each column referenced in condition must unambiguously reference a > > grouping colum > > > > HAVING x> AVG(bar) unambiguously references to a grouping column x > > > > Is this bug ? It is very tedious to repeat same column expression in a > > multiple times: one time in column expression, and n times in having > > clause. > > But you're not referencing x, you're trying to use AVG(bar) in your > expression. > > > I assume it's this way because the standard says so.. one of the more > knowledgable list members will be able to confirm/deny this. > Yes, this behavior is driven by the sql standards. There is actually a very nice paper on this subject if you are interested http://web.onetel.com/~hughdarwen/TheThirdManifesto/Importance-of-Column-Names.pdf -- Robert Treat Build A Brighter Lamp :: Linux Apache {middleware} PostgreSQL
