mysql常用sql语句
show variables like '%max_connections%'; //查看数据库的最大连接数;
SET GLOBAL max_connections=2000;//设置最大连接数，重启后失效，永久生效需要在配置文件中修改。
show PROCESSLIST;//连接详细信息
show status like 'Threads%';//查看连接线程数
show procedure status;//查看存储过程
select count(*) as total from table_name;//查看表有多少条数据
desc table_name; //查看表结构
show table status where comment='view';//查看视图
show index from table_name;// 查看索引
show variables like 'slow_query%';//查看慢查询的日志路径，以及是否开启慢查询。OFF为未开启
show variables like '%version%';查看数据库的版本信息
查看正在执行的事务:
SELECT
trx_id as '事务ID',
trx_state as '事务状态',
trx_requested_lock_id as '事务需要等待的资源',
trx_wait_started as '事务开始等待时间',
trx_tables_in_use as '事务使用表',
trx_tables_locked as '事务拥有锁',
trx_rows_locked as'事务锁定行',
trx_rows_modified as '事务更改行'
FROM information_schema.INNODB_TRX;
查看正在锁的事务：
SELECT
lock_id as '锁ID',
lock_trx_id as '拥有锁的事务ID',
lock_mode as '锁模式',
lock_type as '锁类型',
lock_table as '被锁的表',
lock_index as '被锁的索引',
lock_space as '被锁的表空间号',
lock_page as '被锁的页号',
lock_rec as '被锁的记录号',
lock_data as '被锁的数据'
FROM information_schema.INNODB_LOCKS;
查看正在等待的事务：
SELECT
requesting_trx_id as'请求锁的事务ID',
requested_lock_id as '请求锁的锁ID',
blocking_trx_id as '当前拥有锁的事务ID',
blocking_lock_id as '当前拥有锁的锁ID'
FROM information_schema.INNODB_LOCK_WAITS;