Sergey:

"and closes after the query".

Is that right? I thought that if it was not already opened, you were left with an opened file.

Jim

>>Hi,
>>I am not good in the SQL area, though I own the book "Taming VFP's SQL" by Tamar E. Granor but I just don't have enough time to chew it :)
>>
>>What is the role of index in this case, is WHERE clause in the SELECT command processed by the order of active index?
>
>VFP SQL Engine does not use already open tables or cursors in a query. It open them again similar to USE..AGAIN and closes after the query is complete. As result, active, index, filters, etc. on already open tables have no effect on the query.
>VFP uses Rushmore optimization to speed up queries. In short, it uses existing or temporary indexes (if it can) to process only data that match WHEN or JOIN conditions. You cannot use queries effectively w/o understanding how Rushmore optimization works.