Re: Weird Query

Hi,

 > What exactly do you think is wrong in the results?

The query

   SELECT PP_LOCK FROM cbr_385120060b39d42d8 WHERE PP_LOCK <> '';

Does not return any rows although there definitely is exactly one row that satisfied the condition. This is proven by the result of the query without any constraints.

> You know, the '' is equivalent to NULL.

No, I did not know that. I am used to a ternary logic in SQL servers where NULL does not compare to any "real" values.

But this is not the point here as I am trying to query those records that _do_ have text in that field.

> The first query delivers the 1 existing row with a *NOT NULL* value for
> pp_lock ('STEFANWIMMER\goit consulting\658.1_at_STEFANWIMMER'), all
> following have WHERE CLAUSE evaluated to FALSE and as result no rows
> were returned.

Right. But should not exactly one of

   WHERE PP_LOCK<>''
   WHERE PP_LOCK=''
   WHERE PP_LOCK IS NULL

be TRUE for _any_ value of PP_LOCK? My transscript shows that the sample record is not returned for either constraint. The fourth "IS NOT NULL" does in fact return the record but that is not too surprising :-).

Ciao, MM

-- 
Marian Aldenhövel, Rosenhain 23, 53123 Bonn. +49 228 624013.
http://www.marian-aldenhoevel.de
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