> If I select some fields from mytable with ,where field = XX' or ,where field
>> XX', the indexed fields were read indexed (displayed from IBExpert). But
> If I select some fileds from mytable with 'where field is distinct from XX',
> the read is not indexed.
>
>
>
> It is already okay?

It's an inequality operator, thus, it won't use an index. The same goes
for <> or NOT. Performance wise, try to use an equality operator (or
smaller/greater) whenever you can.



--
With regards,

Thomas Steinmaurer
Upscene Productions
http://www.upscene.com
http://blog.upscene.com/thomas/

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