| From: | Zeugswetter Andreas SB <ZeugswetterA(at)wien(dot)spardat(dot)at> |
|---|---|
| To: | "'Tom Ivar Helbekkmo'" <tih(at)kpnQwest(dot)no> |
| Cc: | "'Tom Lane'" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "'pgsql-hackers(at)postgresql(dot)org'" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | AW: AW: AW: Re: [SQL] behavior of ' = NULL' vs. MySQL v s. S tand ards |
| Date: | 2001-06-07 13:21:22 |
| Message-ID: | 11C1E6749A55D411A9670001FA687963368314@sdexcsrv1.f000.d0188.sd.spardat.at |
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| Lists: | pgsql-hackers |
> > Thus it could be, that NULL in "where column = NULL" is not defined
> > to have a special meaning according to SQL92.
>
> The way I interpret Celko's interpretation of SQL92, that specific
> construct has a meaning; it evaluates to UNKNOWN, thus not to TRUE,
Imho the text refers to a content of a particular column of one particular row.
where table1.col1 = table2.col1
the content of table2.col1 is null --> comparison evaluates to UNKNOWN.
It does not state whether NULL is a valid constant expression.
Andreas
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