[nycphp-talk] Need help understanding NULL
lists at nopersonal.info
lists at nopersonal.info
Sat Aug 29 16:33:13 EDT 2009
Daniel Convissor wrote:
> This is useful, in part, for statistical purposes, since the null record
> won't be added into averages, etc. For example, you had three surveys
> filled out. Two people actually filled in their ages (10 and 20), if you
> do an average when using nulls, you'll get an average age of 15. But if
> you use 0's instead of nulls, the average age will incorrectly be 10.
Dan, this is very helpful--thank you! The light bulb is starting to come
on in my head now...
If anyone else has practical examples, please don't hold back.
Bev
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