SQL 常用语句

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–-表现最差的前10名使用查询
SELECT TOP 
10 ProcedureName 
= t.text, 
ExecutionCount = 
s.execution_count, 
AvgExecutionTime 
= isnull ( s.total_elapsed_time / s.execution_count, 0 
), 
AvgWorkerTime = 
s.total_worker_time / s.execution_count, 
TotalWorkerTime = 
s.total_worker_time, 
MaxLogicalReads = 
s.max_logical_reads, 
MaxPhysicalReads 
= s.max_physical_reads, 
MaxLogicalWrites 
= s.max_logical_writes, 
CreationDateTime 
= s.creation_time, 
CallsPerSecond 
= isnull ( s.execution_count / datediff ( second , s.creation_time, getdate ()), 
0 ) 
FROM 
sys.dm_exec_query_stats s 
CROSS APPLY 
sys.dm_exec_sql_text( s.sql_handle ) t ORDER BY 
s.max_physical_reads DESC
 
--查询显示 CPU 
平均占用率最高的前 50 个 
SQL 语句。 
SELECT TOP 
50
total_worker_time/execution_count AS [Avg CPU Time], 
(SELECT 
SUBSTRING(text,statement_start_offset/2,(CASE WHEN 
statement_end_offset = -1 then 
LEN(CONVERT(nvarchar(max), text)) * 2 
ELSE statement_end_offset end 
-statement_start_offset)/2) 
FROM sys.dm_exec_sql_text(sql_handle)) AS query_text, * 
FROM 
sys.dm_exec_query_stats 
ORDER BY [Avg CPU 
Time] DESC
 
--查看等待sql
select 
s.session_id, 
r.blocking_session_id, 
s.host_name, 
s.login_name, 
databasename=db_name(r.database_id),r.command, r.status as 
sqlexecstatus, 
current_execute_sql = substring(t.text, 
r.statement_start_offset / 2 + 1, 
case
when 
statement_end_offset = -1 then 
len(t.text) 
else 
(r.statement_end_offset - statement_start_offset) / 
2+1
end), 
s.program_name, 
s.status, 
s.cpu_time, 
memory_usage_kb = s.memory_usage * 8, s.reads, s.writes, 
s.transaction_isolation_level, 
c.connect_time, 
c.last_read, c.last_write, 
c.net_transport, c.client_net_address, c.client_tcp_port, 
c.local_tcp_port, 
r.start_time, 
r.wait_time, 
r.wait_type, r.last_wait_type, r.wait_resource, 
r.open_transaction_count, r.transaction_id 
from 
sys.dm_exec_sessions s 
left join 
sys.dm_exec_connections c 
on s.session_id 
= c.session_id 
left join 
sys.dm_exec_requests r 
on s.session_id 
= r.session_id 
and 
c.connection_id = r.connection_id 
outer apply 
sys.dm_exec_sql_text(r.sql_handle) t 
where 
1=1
and 
s.is_user_process = 1
and command is 
not null
 
--查看当前占用 cpu 
资源最高的会话和其中执行的语句(及时CPU)
select * from 
(
select 
spid
,cmd,cpu,physical_io,memusage, 
(select top 
1 [text] from 
::fn_get_sql(sql_handle)) sql_text 
from 
master..sysprocesses 
) t where 
t.sql_text is not null  order by cpu desc,physical_io desc
 
 
--查看缓存中重用次数少，占用内存大的查询语句（当前缓存中未释放的）–全局 
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 
 
SELECT top 
25 qt.text,qs.plan_generation_num,qs.execution_count,dbid,objectid 
FROM 
sys.dm_exec_query_stats qs 
CROSS APPLY 
sys.dm_exec_sql_text(sql_handle) as qt 
WHERE 
plan_generation_num >1
ORDER BY 
qs.plan_generation_num 
 
SELECT top 
50 qt.text AS 
SQL_text ,SUM(qs.total_worker_time) AS total_cpu_time, 
SUM(qs.execution_count) AS total_execution_count, 
SUM(qs.total_worker_time)/SUM(qs.execution_count) AS 
avg_cpu_time, 
COUNT(*) AS 
number_of_statements 
FROM 
sys.dm_exec_query_stats qs 
CROSS APPLY 
sys.dm_exec_sql_text(qs.sql_handle) as qt 
GROUP BY 
qt.text 
ORDER BY 
total_cpu_time DESC --统计总的CPU时间 
--ORDER BY 
avg_cpu_time DESC --统计平均单次查询CPU时间
 
 
 
--TOP 
50 sql
select *,t1.text 
from ( 
SELECT TOP 
50
SUM(qs.total_worker_time) AS total_cpu_time, 
SUM(qs.execution_count) AS total_execution_count, 
COUNT(*) AS 
number_of_statements, 
qs.sql_handle 
FROM 
sys.dm_exec_query_stats AS qs 
 
GROUP BY 
qs.sql_handle 
ORDER BY 
SUM(qs.total_worker_time) DESC 
) t CROSS APPLY 
sys.dm_exec_sql_text( t.sql_handle ) t1
 
 
 
--查询显示缓存计划所占用的 
CPU 总使用率
SELECT 
total_cpu_time, 
total_execution_count,
number_of_statements,
s2.text
--(SELECT 
SUBSTRING(s2.text, statement_start_offset / 2, ((CASE WHEN 
statement_end_offset = -1 THEN 
(LEN(CONVERT(NVARCHAR(MAX), s2.text)) * 2) ELSE statement_end_offset 
END) - statement_start_offset) / 2) ) AS query_text
FROM 
(SELECT TOP 
50
SUM(qs.total_worker_time) AS total_cpu_time, 
SUM(qs.execution_count) AS 
total_execution_count,
COUNT(*) AS 
number_of_statements, 
qs.sql_handle 
--,
--MIN(statement_start_offset) AS statement_start_offset, 
--MAX(statement_end_offset) AS 
statement_end_offset
FROM 
sys.dm_exec_query_stats AS qs
GROUP BY 
qs.sql_handle
ORDER BY 
SUM(qs.total_worker_time) DESC) AS stats
CROSS APPLY 
sys.dm_exec_sql_text(stats.sql_handle) AS s2
 
 
--下面的示例查询显示已重新编译的前 25 
个存储过程。plan_generation_num 指示该查询已重新编译的次数。
select top 
25
sql_text.text,
sql_handle,
plan_generation_num,
execution_count,
dbid,
objectid 
from 
sys.dm_exec_query_stats a
cross apply 
sys.dm_exec_sql_text(sql_handle) as sql_text
where 
plan_generation_num > 1
order by 
plan_generation_num desc
 
 
 
--效率较低的查询计划可能增大 
CPU 占用率。
--下面的查询显示哪个查询占用了最多的 CPU 累计使用率。
SELECT 
highest_cpu_queries.plan_handle, 
highest_cpu_queries.total_worker_time,
q.dbid,
q.objectid,
q.number,
q.encrypted,
q.[text]
from 
(select top 
50
qs.plan_handle, 
qs.total_worker_time
from 
sys.dm_exec_query_stats qs
order by 
qs.total_worker_time desc) as highest_cpu_queries
cross apply 
sys.dm_exec_sql_text(plan_handle) as q
order by 
highest_cpu_queries.total_worker_time desc
 
 
 
--下面的查询显示一些可能占用大量 
CPU 使用率的运算符（例如 ‘%Hash Match%’、‘%Sort%’）以找出可疑对象。
 
select 
*
from 
sys.dm_exec_cached_plans
cross apply 
sys.dm_exec_query_plan(plan_handle)
where 
cast(query_plan 
as nvarchar(max)) like ‘%Sort%‘
or 
cast(query_plan as nvarchar(max)) like ‘%Hash 
Match%‘
 
 
 
--查询哪个查询阻塞了其他的查询
SELECT 
blocked_query.session_id AS blocked_session_id, 
blocking_query.session_id AS blocking_session_id, 
sql_text.text AS 
blocking_text, 
waits.wait_type 
AS blocking_resource 
FROM 
sys.dm_exec_requests blocked_query 
JOIN 
sys.dm_exec_requests blocking_query ON blocked_query.blocking_session_id = 
blocking_query.session_id 
CROSS APPLY 
(SELECT * FROM sys.dm_exec_sql_text(blocking_query.sql_handle) ) sql_text 
JOIN 
sys.dm_os_waiting_tasks waits ON waits.session_id = 
blocking_query.session_id
 
 
 
--运行下面的查询可确定阻塞的会话。
 
select 
blocking_session_id, wait_duration_ms, session_id from 
sys.dm_os_waiting_tasks
where 
blocking_session_id is not null
使用此调用可找出 
blocking_session_id 所返回的 SQL。例如，如果 blocking_session_id 是 87，则运行此查询可获得相应的 SQL。
 
 
 
 
--查看被锁表：
  
select   request_session_id   
spid,OBJECT_NAME(resource_associated_entity_id) tableName   
from   
sys.dm_tran_locks where resource_type=‘OBJECT‘
  
--spid   锁表进程 
--tableName   被锁表名
  
--解锁：
  
declare 
@spid  int
Set 
@spid  = 
57 --锁表进程
declare 
@sql varchar(1000)
set 
@sql=‘kill ‘+cast(@spid  as 
varchar)
exec(@sql)
 
 
检查闩锁等待统计信息以确定 I/O 
瓶颈。运行下面的 DMV 查询以查找 I/O 闩锁等待统计信息。
 
select wait_type, 
waiting_tasks_count, wait_time_ms, signal_wait_time_ms, wait_time_ms / 
waiting_tasks_count
from 
sys.dm_os_wait_stats 
where wait_type 
like ‘PAGEIOLATCH%‘ and 
waiting_tasks_count > 0
order by 
wait_type
如果 
waiting_task_counts 和 wait_time_ms 与正常情况相比有显著变化，则可以确定存在 I/O 问题。获取 SQL Server 
平稳运行时性能计数器和主要 DMV 查询输出的基线非常重要。
这些 wait_types 
可以指示您的 I/O 子系统是否遇到瓶颈。
使用以下 DMV 
查询来查找当前挂起的 I/O 请求。请定期执行此查询以检查 I/O 子系统的运行状况，并隔离 I/O 瓶颈中涉及的物理磁盘。
 
select 
database_id, 
file_id, 
io_stall,
io_pending_ms_ticks,
scheduler_address 
from 
sys.dm_io_virtual_file_stats(NULL, NULL)t1,
sys.dm_io_pending_io_requests as t2
where 
t1.file_handle = t2.io_handle
在正常情况下，该查询通常不返回任何内容。如果此查询返回一些行，则需要进一步调查。
您还可以执行下面的 DMV 
查询以查找 I/O 相关查询。
 
select top 
5 (total_logical_reads/execution_count) as 
avg_logical_reads,
(total_logical_writes/execution_count) as 
avg_logical_writes,
(total_physical_reads/execution_count) as 
avg_physical_reads,
Execution_count, statement_start_offset, p.query_plan, 
q.text
from 
sys.dm_exec_query_stats
cross apply 
sys.dm_exec_query_plan(plan_handle) p
cross apply 
sys.dm_exec_sql_text(plan_handle) as q
order by 
(total_logical_reads + total_logical_writes)/execution_count Desc
 
 
 
 
下面的 DMV 
查询可用于查找哪些批处理/请求生成的 I/O 最多。如下所示的 DMV 查询可用于查找可生成最多 I/O 
的前五个请求。调整这些查询将提高系统性能。
 
select top 
5
(total_logical_reads/execution_count) as 
avg_logical_reads,
(total_logical_writes/execution_count) as 
avg_logical_writes,
(total_physical_reads/execution_count) as 
avg_phys_reads,
Execution_count, 
statement_start_offset as stmt_start_offset, 
sql_handle, 
plan_handle
from 
sys.dm_exec_query_stats 
order by 
(total_logical_reads + total_logical_writes) Desc
 
 
 
–-查询某个数据库的连接数
select count(*) 
from Master.dbo.SysProcesses where dbid=db_id()
 
–-CPU的压力
SELECT 
scheduler_id, current_tasks_count, runnable_tasks_count
FROM 
sys.dm_os_schedulers
WHERE 
scheduler_id < 255
 
 
--查询是否由于连接没有释放引起CPU过高
select * from 
master.dbo.sysprocesses 
where spid> 
50
and waittype = 
0x0000
and waittime = 
0
and status = 
‘sleeping‘
and last_batch 
< dateadd(minute, -10, 
getdate()) 
and login_time 
< dateadd(minute, -10, 
getdate()) 
 
--强行释放空连接
select 
‘kill ‘ + 
rtrim(spid) from master.dbo.sysprocesses 
where spid> 
50
and waittype = 
0x0000
and waittime = 
0
and status = 
‘sleeping‘
and last_batch 
< dateadd(minute, -60, 
getdate()) 
and login_time 
< dateadd(minute, -60, 
getdate())
SQL 常用语句,古老的榕树,5-wow.com