Re: [HACKERS] Phantom row from aggregate in self-join in 6.5
От | Thomas Lockhart |
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Тема | Re: [HACKERS] Phantom row from aggregate in self-join in 6.5 |
Дата | |
Msg-id | 3797E290.4B8E0ABD@alumni.caltech.edu обсуждение исходный текст |
Ответ на | Re: [HACKERS] Phantom row from aggregate in self-join in 6.5 (Tom Lane <tgl@sss.pgh.pa.us>) |
Ответы |
Re: [HACKERS] Phantom row from aggregate in self-join in 6.5
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Список | pgsql-hackers |
> > create table foo (a int); > > select t1.a, count(*) from foo t1, foo t2 group by t1.a; > > I get > > a|count > > -+----- > > | 0 > > (1 row) > > instead of zero rows. > It's not a bug, it's a feature ... or at least there are some around > here who claim that the behavior is OK. I think they're wrong, but > if you want it changed you'll need to cite chapter and verse from the > SQL92 standard, not just assert that Informix does it differently. I don't recall which way I argued before (in fact, I don't recall this particular example), but I do remember arguing (with righteous conviction) that the query select count(*) from foo; should return a single row containing a zero value. Did we infer from that some behavior for "group by" (I can't recall any)? istm, at least today, that the behavior for the group-by is wrong, but we'd better not change the behavior of my example query... - Thomas -- Thomas Lockhart lockhart@alumni.caltech.edu South Pasadena, California
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