[DMV] Missing Index

It help you to find which column you usually use without declaring index field.

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]
  , s.avg_user_impact
  , d.statement AS TableName
  , d.equality_columns 
  , d.inequality_columns
  , d.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