Finding Missing Indexes - Costs

 SET TRANSACTION ISOLATION LEVEL

READ UNCOMMITTED

SELECT TOP 20

 ROUND(s.avg_total_user_cost *

       s.avg_user_impact

        * (s.user_seeks + s.user_scans),0)

                 AS [Total Cost]

 ,d.[statement] AS [Table Name]

 ,equality_columns

 ,inequality_columns

 ,included_columns

FROM sys.dm_db_missing_index_groups g

INNER JOIN sys.dm_db_missing_index_group_stats s

  ON s.group_handle = g.index_group_handle

INNER JOIN sys.dm_db_missing_index_details d

  ON d.index_handle = g.index_handle

ORDER BY [Total Cost] DESC

Author: http://www.i-programmer.info/programming/database/3208-improve-sql-performance-find-your-missing-indexes.html