In this case you don't need compound index because you're using each field separately in your WHERE condition.

>Is there a benefit in terms of Rushmore in creating compound indices for free tables?
>
>For example, when we extract invoice headers, part of the SQL statement might contain "where cCustomer = 'ALLAN' and cInvoiceNo = '123456'".
>Should there be an index on 'cCustomer + cInvoiceNo' as well as 'cCustomer' and 'cInvoicNo'?
>
>TIA.