查询当前正在运行的SQL语句，通过status命令，查看Slow queries这一项，如果值长时间>0,说明有查询执行时间过长

以下为引用的内容：

MySQL> status; 
-------------- 
MySQL Ver 11.18 Distrib 3.23.58, for redhat-Linux-gnu (i386) 
Connection id: 53 
Current database: (null) 
Current user: root@localhost 
Current pager: stdout 
Using outfile: ’’ 
Server version: 5.0.37-log 
Protocol version: 10 
Connection: Localhost via Unix socket 
Client characterset: latin1 
Server characterset: latin1 
Unix socket: /tmp/MySQL.sock 
Uptime: 4 days 16 hours 49 min 57 sec 
Threads: 1 Questions: 706 Slow queries: 0 Opens: 177 Flush tables: 1 Open tables:

52 Queries per second avg: 0.002 
--------------  
 
这时再通过show processlist命令来查看当前正在运行的SQL，从中找出运行慢的SQL语句，找到执行慢的语句后，再用explain命令查看这些语句的执行计划。

MySQL> show processlist;

+----+------+-----------+------+---------+------+-------+------------------+

| Id | User | Host | db | Command | Time | State | Info |

+----+------+-----------+------+---------+------+-------+------------------+

| 53 | root | localhost | NULL | Query | 0 | NULL | show processlist |

+----+------+-----------+------+---------+------+-------+------------------+