NULLs: theoretical problems?

Many discussions point out one deficiency of NULLs: that they collapse
multiple, distinct concepts into one ("no value possible," "value missing,"
"value not available at this time", etc).

What are the other theoretical problems? My impression from skimming some
threads in this ng is that some anomalies might occur, maybe having to do
with NULLs and joins, or NULLs and keys composed of more than one field, but
I'm not sure.


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Relevant Pages

  • Re: NULLs: theoretical problems?
    ... multiple, distinct concepts into one ("no value possible," "value missing," "value not available at this time", etc). ... What are the other theoretical problems? ... My impression from skimming some threads in this ng is that some anomalies might occur, maybe having to do with NULLs and joins, or NULLs and keys composed of more than one field, but I'm not sure. ...
    (comp.databases.theory)
  • Re: Difference between = and IN
    ... I was under the impression that Nulls would just be excluded from the ... "Hugo Kornelis" wrote: ... > subquery is executed only once. ...
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  • Re: NULLs: theoretical problems?
    ... What are the other theoretical problems? ... My impression from skimming some ... with NULLs and joins, or NULLs and keys composed of more than one field, ...
    (comp.databases.theory)