Brenda,

I assume that you are talking about VFP's SQL - Select and related commands.

Yes, it does use indexes, extensively!

The WHERE clause (as well as the JOIN) fields are what you need indexes on.

You are reading up on optimizing, so you will also read that there are RULES related to the coding of TAG definitions and exactly matching WHERE clause field specifications.

Even if your application seems to run acceptably fast now for the users, if you have SQLs in it then they will see dramatic improvements if you adopt these things.

If you are lucky, you may not need to make many changes to your coding. Depends on whether you have been consistent in how you have coded each different field in each WHERE clause from SQL statement to SQL statement. If they are all - for each independent field - the same then as long as you create TAGs on those fields exactly the same way then no code at all needs changing.

By the way, this is what "Rushmore" is all about.

good luck,

Jim Nelson

>I had thought SQL does not use indexes. But in the Developer's Guide it says 'you should also index any fields involved in a join.'
>
>Also, what is the rule of thumb on number of indexes. Mainly how the number of indexes affect updating times.
>
>Looking for optimization information. Have always had my app in a small office with workers who are in the same office. Now they want to use it for the state of VA. Trying to learn about optimization tips and tricks .. and knowledge.
>
>Thanks
>
>Brenda