利用DMV找出查询最慢的语句

SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED

SELECT TOP 20 
CAST(qs.total_elapsed_time/1000000.0 AS DECIMAL(28,2)) AS [Total Elaspsed Duration(s)],
qs.execution_count, 
SUBSTRING(qt.text,
            (qs.statement_start_offset/2)+1,
            ((CASE WHEN qs.statement_end_offset = -1 
                THEN LEN(CONVERT(NVARCHAR(MAX),qt.text))*2
                ELSE qs.statement_end_offset 
                END - qs.statement_start_offset)/2)+1) 
AS [Individual Query],
qt.text AS [Parent Query], 
DB_NAME(qt.dbid) AS DatabaseName, 
qp.query_plan
FROM SYS.dm_exec_query_stats qs
CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) qt
CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle) qp
ORDER BY total_elapsed_time DESC