SQLServer常用查询方法总结

1、查询sql server数据库中某表（tablename）的读写次数：

SELECT  OBJECT_SCHEMA_NAME(ddius.object_id) + '.' + OBJECT_NAME(ddius.object_id) AS [Object Name],
        CASE WHEN (SUM(user_updates + user_seeks + user_scans + user_lookups)=0) THEN NULL
             ELSE CONVERT(DECIMAL(38,2),CAST(SUM(user_seeks + user_scans + user_lookups) AS DECIMAL)
                  / CAST(SUM(user_updates + user_seeks + user_scans + user_lookups) AS DECIMAL))
        END AS [Proportion of Reads],
        CASE WHEN (SUM(user_updates + user_seeks + user_scans + user_lookups)=0) THEN NULL
             ELSE CONVERT(DECIMAL(38,2),CAST(SUM(user_updates) AS DECIMAL)
                  / CAST(SUM(user_updates + user_seeks + user_scans + user_lookups) AS DECIMAL))
        END AS [Proportion of Writes],SUM(user_seeks + user_scans + user_lookups) AS [Total Read Operations],
        SUM(user_updates) AS [Total Write Operations]
FROM    sys.dm_db_index_usage_stats AS ddius
JOIN    sys.indexes AS i ON ddius.object_id=i.object_id
                            AND ddius.index_id=i.index_id
WHERE   i.type_desc IN ('CLUSTERED','HEAP') --only works in Current db
AND OBJECT_NAME(ddius.object_id)='tablename'
GROUP BY ddius.object_id
ORDER BY OBJECT_SCHEMA_NAME(ddius.object_id) + '.' + OBJECT_NAME(ddius.object_id);

–一般排查都是用下面的脚本，一般会用到三个视图sys.sysprocesses ,dm_exec_sessions ,dm_exec_requests
2、当前的数据库用户连接

SELECT * FROM sys.[sysprocesses] WHERE [spid]>50 and DB_NAME([dbid])='BPMProduct_ZLDC_5.1';
SELECT COUNT(*) FROM [sys].[dm_exec_sessions] WHERE [session_id]>50

3、前10个最耗CPU时间的会话

SELECT TOP 10
[session_id],
[request_id],
[start_time] AS '开始时间',
[status] AS '状态',
[command] AS '命令',
dest.[text] AS 'sql语句', 
DB_NAME([database_id]) AS '数据库名',
[blocking_session_id] AS '正在阻塞其他会话的会话ID',
[wait_type] AS '等待资源类型',
[wait_time] AS '等待时间',
[wait_resource] AS '等待的资源',
[reads] AS '物理读次数',
[writes] AS '写次数',
[logical_reads] AS '逻辑读次数',
[row_count] AS '返回结果行数'
FROM sys.[dm_exec_requests] AS der 
CROSS APPLY 
sys.[dm_exec_sql_text](der.[sql_handle]) AS dest 
WHERE [session_id]>50 AND DB_NAME(der.[database_id])='BPMProduct_ZLDC_5.1' 
ORDER BY [cpu_time] DESC

–在SSMS里选择以文本格式显示结果

SELECT TOP 10 
dest.[text] AS 'sql语句'
FROM sys.[dm_exec_requests] AS der 
CROSS APPLY 
sys.[dm_exec_sql_text](der.[sql_handle]) AS dest 
WHERE [session_id]>50 
ORDER BY [cpu_time] DESC

4、查看CPU数和user scheduler数目

–查看CPU数和user scheduler数和最大工作线程数，检查worker是否用完也可以排查CPU占用情况

SELECT cpu_count,scheduler_count FROM sys.dm_os_sys_info

5、查看最大工作线程数

SELECT max_workers_count FROM sys.dm_os_sys_info

SELECT
scheduler_address,
scheduler_id,
cpu_id,
status,
current_tasks_count,
current_workers_count,active_workers_count
FROM sys.dm_os_schedulers

6、查看等待资源

–如果SQLSERVER存在要等待的资源，那么执行下面语句就会显示出会话中有多少个worker在等待

SELECT TOP 10
[session_id],
[request_id],
[start_time] AS '开始时间',
[status] AS '状态',
[command] AS '命令',
dest.[text] AS 'sql语句', 
DB_NAME([database_id]) AS '数据库名',
[blocking_session_id] AS '正在阻塞其他会话的会话ID',
der.[wait_type] AS '等待资源类型',
[wait_time] AS '等待时间',
[wait_resource] AS '等待的资源',
[dows].[waiting_tasks_count] AS '当前正在进行等待的任务数',
[reads] AS '物理读次数',
[writes] AS '写次数',
[logical_reads] AS '逻辑读次数',
[row_count] AS '返回结果行数'
FROM sys.[dm_exec_requests] AS der 
INNER JOIN [sys].[dm_os_wait_stats] AS dows 
ON der.[wait_type]=[dows].[wait_type]
CROSS APPLY 
sys.[dm_exec_sql_text](der.[sql_handle]) AS dest 
WHERE [session_id]>50 
ORDER BY [cpu_time] DESC

7、查询CPU占用高的语句

SELECT TOP 10
total_worker_time/execution_count AS avg_cpu_cost, plan_handle,
execution_count,
(SELECT SUBSTRING(text, statement_start_offset/2 + 1,
(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_cost] DESC

8、查询缺失索引

SELECT 
DatabaseName = DB_NAME(database_id)
,[Number Indexes Missing] = count(*) 
FROM sys.dm_db_missing_index_details
GROUP BY DB_NAME(database_id)
ORDER BY 2 DESC;

SELECT TOP 10 
[Total Cost] = ROUND(avg_total_user_cost * avg_user_impact * (user_seeks + user_scans),0) 
, avg_user_impact
, TableName = statement
, [EqualityUsage] = equality_columns 
, [InequalityUsage] = inequality_columns
, [Include Cloumns] = included_columns
FROM sys.dm_db_missing_index_groups g 
INNER JOIN sys.dm_db_missing_index_group_stats s 
ON s.group_handle = g.index_group_handle 
INNER JOIN sys.dm_db_missing_index_details d 
ON d.index_handle = g.index_handle
ORDER BY [Total Cost] DESC;