Re: sql question...

On Thu, 12 Jun 1997 15:22:59 -0400, oispeggy_at_acsu.buffalo.edu wrote:

>
>Learn something new every day....
>
>1.
>select lname, fname This returns everyone with 'N' or 'G' or ' '.
>from resdemo None with 'Y'. None with null.
>where fellow != 'Y'
>

 <snip>
>
>
>What surprised me is that #1 did not return anyone with a null value?
>I thought it would? Why didn't it?
>

Basically, NULL values are ignored in any test using comparison operators (=, !=, >, <, etc.). In order to cater for NULL values, you either have to wrap NVL around the item, or explicitly use the IS (NOT) NULL operator.

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