RE: Counterquestion - is Oracle a He or a She - or an It or a hermaphrodite
- From: Charlotte Hammond <charlottejanehammond@xxxxxxxxx>
- To: ORACLE-L <oracle-l@xxxxxxxxxxxxx>
- Date: Tue, 2 Aug 2005 04:48:42 -0700 (PDT)
It's certainly a nice shortcut to do this with empty
strings but by analogy with other data types this
sounds like cheating.... ;-)
If you have, say, graduation dates for students and
some students drop-out and do not complete their
courses, you cannot set the "empty date" for their
graduation - there is no such thing - even though you
KNOW that they do not have a graduation date.
You'd have to set it NULL and use some other attribute
to distinguish them from students who have not dropped
out but have not yet completed their course.
- Charlotte
-----Original Message-----
Quite simply, and the most easily understood example I
know, some people
have no middle name.
In that case, the value of the string of that person's
middle name is not
NULL, but rather the
accurate value for the person's middle name is the
empty string. The value
is absolutely known,
whereas the NULL value is definitely not known.
I don't know a better way to explain it than that.
Regards,
mwf
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