On 8/23/07, Florian G. Pflug <[EMAIL PROTECTED]> wrote: > Ben Tilly wrote: > > On 8/22/07, Michael Glaesemann <[EMAIL PROTECTED]> wrote: > >> On Aug 22, 2007, at 20:49 , Ben Tilly wrote: > >> > >>> If your implementation accepts: > >>> > >>> group by case when true then 'foo' end > >> What would that mean? Regardless of whether or not it's accepted, it > >> should have *some* meaning. > > > > To my eyes it has a very clear meaning, we're grouping on an > > expression that happens to be a constant. Which happens to be the > > same for all rows. Which is a spectacularly useless thing to actually > > do, but the ability to do it happens to be convenient when I'm looking > > for something to terminate a series of commas in a dynamically built > > query. > > Which is the same very clear meaning that "group by 1" has - we're > grouping on a expression which happens to be the constant 1. Hey, > wait a second. This isn't what "group by 1" means at all - it > rather means group by whatever the fist column in the select list is.
Which feature shocked me when I first saw it in Oracle. It violated every expectation that I have. I also deliberately do NOT use that feature. Because it is not safe if someone else is possibly going to edit your query. Add a field in a natural place and, oops, your query just broke. Also I hate referring to things by position in code. Particularly when they are far away from each other as they may be in a large query. (I've written queries that are over 1000 lines long in the past.) > So, yes, "group by 'foo'" *seems* to have a very clear meaning - but > that clearness vanishes as soon as you take into account what "group by 1" > means. I'm happy to use "group by 'foo'::text" instead. Anyone else in my position will have to stumble on their own solution, but I don't think there are that many in my position. Cheers, Ben ---------------------------(end of broadcast)--------------------------- TIP 7: You can help support the PostgreSQL project by donating at http://www.postgresql.org/about/donate