RE: Counterquestion - is Oracle a He or a She - or an It or a hermaphrodite

From: Charlotte Hammond <charlottejanehammond_at_yahoo.com>
Date: Tue, 2 Aug 2005 04:48:42 -0700 (PDT)
Message-ID: <20050802114842.24753.qmail@web33111.mail.mud.yahoo.com>

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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Received on Tue Aug 02 2005 - 06:50:38 CDT