>In this statement : "select * from db where cnum = 'c'".
>
>I want that query return only one record and the query stop after find one record. I don't want that the query scan all the database for it.
>
>What I can append to this query to do it?

Forgot something in the first answer:

the TOP clause won't make the select faster, because it's applied to the result set of the select, and not to the original table ! You may add an order clause to have more control about which will be your TOP 1 record. Maybe native xBase commands will do the work better.