Help with composite indices

I've read how to create a composite index, but I'm unsure about how to use one to order output or join tables. In my db, I have tables with company id's and dates, with the combination of id and date being unique. So I can create an index on (id, date). Can I use that index for joining tables? Can I use that index when I come to the "order by" part of a select statement? Many thanks. -- -------------------------------------------------------------------- Bradford Young E-mail: byoung@cornercap.com Cornerstone Capital Corp. Tel: (404) 870-0700 Atlanta, GA Fax: (404) 870-0770