Re: NULLs ;-)
От | Ragnar |
---|---|
Тема | Re: NULLs ;-) |
Дата | |
Msg-id | 1164728649.27070.167.camel@localhost.localdomain обсуждение исходный текст |
Ответ на | Re: NULLs ;-) ("John D. Burger" <john@mitre.org>) |
Ответы |
Re: NULLs ;-)
Re: NULLs ;-) |
Список | pgsql-general |
On þri, 2006-11-28 at 09:42 -0500, John D. Burger wrote: > Scott Ribe wrote: > > > where a <> b or (a is null and b is not null) or (a is not null and > > b is null) > > In the absence of IS DISTINCT FROM, I think this has the same semantics: > > where coalesce(a, b) <> coalesce(b, a) sorry, but no. test=# create table logic (a int, b int); CREATE TABLE test=# insert into logic values (null,null); INSERT 34495399 1 test=# insert into logic values (null,1); INSERT 34495400 1 test=# insert into logic values (1,null); INSERT 34495401 1 test=# insert into logic values (1,1); INSERT 34495402 1 test=# select a,b, coalesce(a, b) <> coalesce(b, a) as coal, a IS DISTINCT FROM b as dist from logic; a | b | coal | dist ---+---+------+------ | | | f | 1 | f | t 1 | | f | t 1 | 1 | f | f (4 rows) test=# gnari
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