[nycphp-talk] Need help understanding NULL
tedd at sperling.com
Sat Aug 29 19:30:12 EDT 2009
At 4:33 PM -0400 8/29/09, lists at nopersonal.info wrote:
>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.
Null is an odd critter. It's not an empty string, it's not '', it's
not 0, it's NULL.
Try reading this:
http://sperling.com http://ancientstones.com http://earthstones.com
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