| From: | Tom Ivar Helbekkmo <tih(at)kpnQwest(dot)no> |
|---|---|
| To: | Zeugswetter Andreas SB <ZeugswetterA(at)wien(dot)spardat(dot)at> |
| 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: | Re: AW: Re: [SQL] behavior of ' = NULL' vs. MySQL vs. Stand ards |
| Date: | 2001-06-07 20:28:16 |
| Message-ID: | 86ofs0m3vj.fsf@athene.i.eunet.no |
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| Lists: | pgsql-hackers |
Zeugswetter Andreas SB <ZeugswetterA(at)wien(dot)spardat(dot)at> writes:
> Actually I am not sure whether the column = NULL syntax is even
> defined or allowed in SQL92
I've just checked, by reading the relevant paragraphs and studying the
BNF, and the standard says that any comparison of the form X <comp op>
Y is unknown if X or Y (or both) is NULL, including the case where
NULL is given as an explicit constant. So, SQL92 clearly demands that
"column = NULL" is UNKNOWN, never TRUE or FALSE.
-tih
--
The basic difference is this: hackers build things, crackers break them.
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