1、查看CPU占用量最高的会话及SQL语句

select spid,cmd,cpu,physical_io,memusage,
(select top 1 [text] from ::fn_get_sql(sql_handle)) sql_text
from master..sysprocesses order by cpu desc,physical_io desc

2、查看缓存重用次数少，内存占用大的SQL语句　

SELECT TOP 100 usecounts, objtype, p.size_in_bytes,[sql].[text] 
FROM sys.dm_exec_cached_plans p OUTER APPLY sys.dm_exec_sql_text (p.plan_handle) sql 
ORDER BY usecounts,p.size_in_bytes  desc

3、执行最慢的SQL语句

SELECT
 (total_elapsed_time / execution_count)/1000 N'平均时间ms'
 
,total_elapsed_time/1000 N'总花费时间ms'
 
,total_worker_time/1000 N'所用的CPU总时间ms'
 
,total_physical_reads N'物理读取总次数'
 
,total_logical_reads/execution_count N'每次逻辑读次数'
 
,total_logical_reads N'逻辑读取总次数'
 
,total_logical_writes N'逻辑写入总次数'
 
,execution_count N'执行次数'
 
,SUBSTRING(st.text, (qs.statement_start_offset/2) + 1,
 
((CASE statement_end_offset
 WHEN -1 THEN DATALENGTH(st.text)
 ELSE qs.statement_end_offset END
 
 - qs.statement_start_offset)/2) + 1) N'执行语句'
 
,creation_time N'语句编译时间'
 
,last_execution_time N'上次执行时间'
 
FROM
 
sys.dm_exec_query_stats AS qs CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) st
 
WHERE
 
SUBSTRING(st.text, (qs.statement_start_offset/2) + 1,
 
((CASE statement_end_offset
 
WHEN -1 THEN DATALENGTH(st.text)
 
ELSE qs.statement_end_offset END
 
- qs.statement_start_offset)/2) + 1) not like 'tch%'
 
ORDER BY
 total_elapsed_time / execution_count DESC;

4、总耗CPU最多的前个SQL

SELECT TOP 20
    total_worker_time/1000 AS [总消耗CPU 时间(ms)],execution_count [运行次数],
    qs.total_worker_time/qs.execution_count/1000 AS [平均消耗CPU 时间(ms)],
    last_execution_time AS [最后一次执行时间],max_worker_time /1000 AS [最大执行时间(ms)],
    SUBSTRING(qt.text,qs.statement_start_offset/2+1,
        (CASE WHEN qs.statement_end_offset = -1
        THEN DATALENGTH(qt.text)
        ELSE qs.statement_end_offset END -qs.statement_start_offset)/2 + 1)
    AS [使用CPU的语法], qt.text [完整语法],
    qt.dbid, dbname=db_name(qt.dbid),
    qt.objectid,object_name(qt.objectid,qt.dbid) ObjectName
FROM sys.dm_exec_query_stats qs WITH(nolock)
CROSS apply sys.dm_exec_sql_text(qs.sql_handle) AS qt
WHERE execution_count>1
ORDER BY  total_worker_time DESC

5、平均耗CPU最多的前个SQL

SELECT TOP 20
    total_worker_time/1000 AS [总消耗CPU 时间(ms)],execution_count [运行次数],
    qs.total_worker_time/qs.execution_count/1000 AS [平均消耗CPU 时间(ms)],
    last_execution_time AS [最后一次执行时间],min_worker_time /1000 AS [最小执行时间(ms)],
    max_worker_time /1000 AS [最大执行时间(ms)],
    SUBSTRING(qt.text,qs.statement_start_offset/2+1,
        (CASE WHEN qs.statement_end_offset = -1
        THEN DATALENGTH(qt.text)
        ELSE qs.statement_end_offset END -qs.statement_start_offset)/2 + 1)
    AS [使用CPU的语法], qt.text [完整语法],
    qt.dbid, dbname=db_name(qt.dbid),
    qt.objectid,object_name(qt.objectid,qt.dbid) ObjectName
FROM sys.dm_exec_query_stats qs WITH(nolock)
CROSS apply sys.dm_exec_sql_text(qs.sql_handle) AS qt
WHERE  execution_count>1
ORDER BY (qs.total_worker_time/qs.execution_count/1000) DESC

参考资料：https://www.cnblogs.com/approx/p/12038967.html