在MySQL中，使用以下SQL命令来查看当前的连接数：
SHOW STATUS WHERE `variable_name` = 'Threads_connected';
删除某些链接数
查看当前连接的会话
SHOW PROCESSLIST;
SHOW FULL PROCESSLIST;
kill 会话ID;
拼接kill 进程id的慢sql
select concat('kill ', id, ';') from information_schema.PROCESSLIST where COMMAND != 'Sleep' and time > 2*60 ORDER BY TIME DESC\G;
