[nycphp-talk] Need help understanding NULL

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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.


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