Yes there is. According to Date (tm) (and to SQL92), =NULL should always return false. Certain databases (cough access cough) allow that and translate =null to 'is null', however, the standards say it should not be done.
You may experience severe lossage if you rely on it, as some databases change their implementation of '=null' even between versions. -alex On Tue, 23 Oct 2001, Sterin, Ilya wrote: > So if NULL is not defined, what's the difference between "is NULL" and > "=NULL". I guess my disagreement comes from not being able to ask for > undefined field by =undefined, but rather is undefined. It's all a matter > of syntax and I doubt there is a theoretical explanation for this in SQL, or > maybe there are lots:-). Though the way that DB vendors implement their SQL > engines prevents (in many cases) in easily reusing the query using > placeholders, of course there are many ways around. > This is getting OT, unless it will in some ways spark any ideas for DBI/DBD > patches. > > Ilya > > -----Original Message----- > From: Bud Rogers > To: [EMAIL PROTECTED] > Sent: 10/23/01 4:07 PM > Subject: Re: = NULL vs. IS NULL > > On Tuesday 23 October 2001 16:56 pm, Bart Lateur wrote: > > On Tue, 23 Oct 2001 12:35:57 -0500, Stephen Clouse wrote: > > > > >This is not Oracle, but ANSI-standard behavior. NULL represents the > absence or > > >non-existence of a value. A non-existent value cannot be equal to > anything. So > > >this is the correct behavior. I personally don't think DBI should > muck > with > > >proper behavior. > > > > My personal opinion is to disagree. To me, NULL means "empty". It is > not > > the same as a zero length string. But empty is empty, thus NULL=NULL. > > > > Nitpicking that NULL != NULL, is only making our life harder. > > > > Last week, there was a similar discussion going on, on the Perl6 > mailing > > lists, with regards to NaN (Not A Number). Is NaN==Nan, or NaN!=NaN? > > Bruce Momjian spends a couple of paragraphs in the elephant book > explaining > why NULL doesn't equal anything, including NULL. NULL is not NaN, NULL > is > undefined. > >
