Use SSMS to run your query and activate the "execution plan". It will tell you which index are used (if any). The SQL engine is automatically using indexes when the query optimizer determines that it will be helpful.
See
http://www.emoreau.com/Entries/Blogs/2008/05/Everything-you-want-to-know-about-Microsoft-SQL-Execution-plans.aspx>Does Microsoft's SQL 2005 use Rushmore technology?
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>If I have two indexes on two different fields in a table and perform a SELECT query on those two fields, will the server use the indexes automatically (in an optimized / fast search) or will it perform like the LOCATE command without rushmore, and search through the entire database on the server?
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>Do I have to be explicit with the index usage when performing a query or is it all taken care of by the server provided I have the indexes in place?
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>Thank you in advance.
Éric Moreau, MCPD, Visual Developer - Visual Basic MVP
Conseiller Principal / Senior Consultant
Moer inc.
http://www.emoreau.com