A query for asking SQL Server about performance recommendations AKA "Missing Indices"

Missing Index.sql

-- Missing Index Script
-- Original Author: Pinal Dave 
SELECT TOP 25
dm_mid.database_id AS DatabaseID,
dm_migs.avg_user_impact*(dm_migs.user_seeks+dm_migs.user_scans) Avg_Estimated_Impact,
dm_migs.last_user_seek AS Last_User_Seek,
OBJECT_NAME(dm_mid.OBJECT_ID,dm_mid.database_id) AS [TableName],
'CREATE INDEX [PERF_' + OBJECT_NAME(dm_mid.OBJECT_ID,dm_mid.database_id) + '_'
+ REPLACE(REPLACE(REPLACE(ISNULL(dm_mid.equality_columns,''),', ','_'),'[',''),']','') 
+ CASE
WHEN dm_mid.equality_columns IS NOT NULL
AND dm_mid.inequality_columns IS NOT NULL THEN '_'
ELSE ''
END
+ REPLACE(REPLACE(REPLACE(ISNULL(dm_mid.inequality_columns,''),', ','_'),'[',''),']','')
+ ']'
+ ' ON ' + dm_mid.statement
+ ' (' + ISNULL (dm_mid.equality_columns,'')
+ CASE WHEN dm_mid.equality_columns IS NOT NULL AND dm_mid.inequality_columns 
IS NOT NULL THEN ',' ELSE
'' END
+ ISNULL (dm_mid.inequality_columns, '')
+ ')'
+ ISNULL (' INCLUDE (' + dm_mid.included_columns + ')', '') AS Create_Statement
FROM sys.dm_db_missing_index_groups dm_mig
INNER JOIN sys.dm_db_missing_index_group_stats dm_migs
ON dm_migs.group_handle = dm_mig.index_group_handle
INNER JOIN sys.dm_db_missing_index_details dm_mid
ON dm_mig.index_handle = dm_mid.index_handle
WHERE dm_mid.database_ID = DB_ID()
ORDER BY Avg_Estimated_Impact DESC
GO