On Thu, Sep 29, 2005 at 09:38:54AM +0100, BogDan Vatra wrote: > > The following bug has been logged online: > > Bug reference: 1921 > Logged by: BogDan Vatra > Email address: [EMAIL PROTECTED] > PostgreSQL version: 8.0.3 > Operating system: win xp pro > Description: NULL<>NULL ?!?!?!?!?!?!? > Details: > > Please execute this query: > > create table test (id serial, tt varchar(50)); > insert into test (tt) values(NULL); > select tt from test where tt=NULL; > > This should return 1 row but ... > An then try > > select tt from test where tt<>NULL; > > 0 row(s) !!!
It is not a bug. NULL isn't a datum. It's a state of ignorance. If I don't know what your birthday is and I don't know what your coworker's birthday is, I also don't know whether they are equal, and so the only right answer to "Is BogDan's birthday unequal to his coworker's?" is "I don't know." HTH :) Cheers, D -- David Fetter [EMAIL PROTECTED] http://fetter.org/ phone: +1 510 893 6100 mobile: +1 415 235 3778 Remember to vote! ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
