Thanks That helps
Jon

>Your rule is essentially correct.
>
>You said your index is INDEX ON A+B TAG SOMETAG
>
>You SELECT commands won't use this tag as they stand. The SQL commands you wrote would benefit from indexes like these...
>
>INDEX ON A TAG ATAG
>INDEX ON B TAG BTAG
>
>In order to do an SQL command that uses the first index, you must...
>
>SELECT WHERE A+B = vp_A+vp_B.
>
>If you try ...
>
>SELECT WHERE B+A = vp_B+vp_A. This would be slow because it isn't using any of the indexes.
>
>>Example:
>>If my index on a table is A + B
>>(two chacter based fields to keep things simple) and I then have
>>
>>SELECT statement with WHERE B = vp_B AND A = vp_A
>>
>>will this run at the same speed as the same as
>>
>>SELECT statement but with WHERE A = vp_A AND B = vp_B
>>
>>Thanks
>>Jon