--关于语句执行的基本情况
 select * from sys.dm_exec_query_stats

 --动态管理函数  需要提供参数
  select top 10 execution_count,total_worker_time,t.text,total_worker_time/execution_count    
  as avgcpu from  sys.dm_exec_query_stats as s
  cross apply sys.dm_exec_sql_text(s.sql_handle) as t
  order by avgcpu desc

  --当前正在等待cpu执行的任务数
  select runnable_tasks_count from sys.dm_os_schedulers where runnable_tasks_count>0

  --内存方面的动态管理视图
  select * from sys.dm_os_memory_cache_clock_hands where rounds_count>0
   and removed_all_rounds_count>0

 --评估哪些语句浪费SQL性能
	SELECT * FROM sys.dm_exec_query_stats
	-- 所需时间除以执行次数
	select top 10 total_elapsed_time/execution_count as avgtotal,t.text  from sys.dm_exec_query_stats as  s
	--关于语句的信息
	cross apply sys.dm_exec_sql_text(s.sql_handle) as t
	order by avgtotal desc

	--评估数据库io 的问题
	select * from sys.dm_io_pending_io_requests  -- 挂起io的请求  视图
	select * from sys.dm_io_virtual_file_stats((select DB_ID(‘AdventureWorks2014‘)),null)  --函数   返回数据和日志文件的 I/O 统计信息
	
	--说明文件是被挂起的
	select s.file_id,r.io_pending from sys.dm_io_pending_io_requests as r inner join
	sys.dm_io_virtual_file_stats((select DB_ID(‘AdventureWorks2014‘)),null) as s
	 on r.io_handle=s.file_handle

 create database  HRDB
	 go 
	 use HRDB
	 go 
	 create table t1(c1 int,c2 int)
	 go
	 insert t1 values(1,1)

begin tran
	 update t1 set c1=2 where c1=1
	 --并不结束

--语句被阻塞
select * from t1

 --查看系统阻塞的情况
	 select * from master..sysprocesses
	 select distinct
	 ‘PID‘=str(s.spid,4),	
	 ‘BLOCKID‘=str(s.blocked,4),
	 ‘Status‘ =
	 case s.status
	 when ‘sleeping‘ then ‘Running‘ 
	 when ‘runnalbe‘ then ‘Complete‘
	 when ‘suspended‘ then ‘Blocked‘
	 end,t.text
	 from master..sysprocesses as s cross apply sys.dm_exec_sql_text(s.sql_handle) as t
	 where s.dbid=(select DB_ID(‘hrdb‘))

commit    select * from t1