On Wed, Nov 30, 2005 at 01:20:19PM -0500, John D. Burger wrote: > >select p1.gazPlaceID > > from gazPlaces as p1 > > join gazNamings as n1 using (gazPlaceID) > > join gazContainers as c1 using (gazPlaceID) > > group by p1.gazPlaceID, p1.featureType, n1.placeNameID, > >c1.containerID > > having count(*) = 1 > > The problem is that then every row is unique, because gazPlaceID is a > primary key. As far as I can see, I need to group on just the other > three columns - they're the ones for which I'm interested in > uniqueness.
AIUI, according to the JOIN conditions in the query you have n1.gazPlaceID = c1.gazPlaceID = p1.gazPlaceID so grouping by one of those shouldn't affect the query result. Are the tables wide? Maybe you're losing a lot of time transferring data you don't need. Other than that I can't think of any neat tricks... Have a nice day, -- Martijn van Oosterhout <kleptog@svana.org> http://svana.org/kleptog/ > Patent. n. Genius is 5% inspiration and 95% perspiration. A patent is a > tool for doing 5% of the work and then sitting around waiting for someone > else to do the other 95% so you can sue them.
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