An index contains key values built from one or more columns in a table. These keys are stored in a structure that allows SQL Server to find rows associated with the key values quickly and efficiently. You can have only one clustered index, create clustered index on a column for eg. employee_id which would be always unique. Your inserts, updates and deletes would definetly become more faster. But before creating index on the table drop all the current indexes and recreate the clustered index. for more help go to MSDN help, or refer to books online of sql server.