Martijn Tonies wrote:

> Hi,
>
>
>> I'm using FIREBIRD 1.5 and I have a question.
>> What SQL has the best performance ?
>>
>> 1) select * from planoconta where nivel like '01.01%'
>>
>> or
>>
>> 2) select * from planoconta where substring(nivel from 1 for 5) =
>
> '01.01'
>
> If you have an index of NIVEL, the first one is the
> fastest.
>
> The second one cannot use an index.

"cannot"? A smart optimizer should be able to use an index here, but Fb's
probably won't.


--
Aage J.