Re: Subselects open issue Nr. NEW
От | Vadim B. Mikheev |
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Тема | Re: Subselects open issue Nr. NEW |
Дата | |
Msg-id | 34E90484.A150B16@sable.krasnoyarsk.su обсуждение исходный текст |
Ответ на | Subselects open issue Nr. NEW ("Vadim B. Mikheev" <vadim@sable.krasnoyarsk.su>) |
Ответы |
Re: [HACKERS] Re: Subselects open issue Nr. NEW
Re: [HACKERS] Re: Subselects open issue Nr. NEW |
Список | pgsql-hackers |
Michael Hirohama wrote: > > [...] > >SQL> select * from a where (x,z) >= ANY (select y, l from b); > >select * from a where (x,z) >= ANY (select y, l from b) > > * > >ERROR at line 1: > >ORA-00920: invalid relational operator > > > >: only '=' and '<>' are allowed if there are more than one > >expression on the left side of clause with subselect... > > > >Is this in standard or Oracle' preference ? > > This is a mathematical law. > > Vectors cannot be strictly ordered. "Partial orderings" are possible. > > Let A be (1, 2) > Let B be (4, 7) > Let C be (3, 5) > Let D be (5, 10) > > A is smallest; D is largest; how do B and C relate? I understand this. And this is how it works currently: select * from tab where (A,B) >= ANY (select X, Y from tab2); means: select tuples where A >= X _and_ B >= Y for some tuple from tab2. ^^^^^ 'AND' is used for all Op-s except for '<>' when 'OR' is used. Question is "should we drop this feature (?) or leave it as is ?" Comments ? Vadim
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