MySQL: 常用命令

Posted 2021-09-13 尊宝雷

1、查看慢查询超时时间值
use performance_schema;
select * from variables_by_thread where variable_name = \'long_query_time\';

2、查看mysql当前线程
show processlist;

3、创建wayne用户，设置密码，允许所有网段访问
use performance_schema;
1. create user \'wayne\'@\'%\' identified by \'123\';
drop user \'wayne\'@\'%\';
2. create user \'wayne\'@\'192.168.32.%\' identified by \'123\';
drop user \'wayne\'@\'192.168.32.%\';
3. show grants;  查看用户权限
show grants for \'wayne\'@\'%\';  查看\'wayne\'@\'%\'用户权限
4. grant select,update,insert,delete on test.* to \'wayne\'@\'%\';  赋予\'wayne\'@\'%\'用户对test库下所有tables增删改查的权限
5. alter user \'wayne\'@\'%\' identified by \'456\';  修改用户密码
6. grant create,index on test.* to \'wayne\'@\'%\';  给用户添加create、index权限
7. revoke create,index on test.* to \'wayne\'@\'%\'; 收回用户的create、index权限
revoke all on test.* to \'wayne\'@\'%\'; 收回用户的所有权限
flush privileges;  
8. grant create,index on test.* to \'wayne\'@\'%\' with grant aption; 给wayne用户赋予可以赋予其他用户权限的权限
9. alter user \'wayne\'@\'%\' with max_user_connections 1; 用户最大连接数限制
10. update mysq.user set Host=\'%\'  where User=\'root\' and Host=\'0.0.0.0\'; 设置所有用户可以使用root用户访问数据库

4、MySQL日志设置开启

1. show variables like \'%log%\'; 查看慢查询配置；
2. set global slow_query_log=\'ON\'; 
3. set global slow_query_log_file=\'/usr/local/mysql/data/slow_query.log\';
4. set global long_query_time=1;

修改my.cnf配置文件后，重启MySQL服务
[mysqld]
slow_query_log = ON
slow_query_log_file = /usr/local/mysql/data/slow_query.log
long_query_time = 1

5、修改数据库、表的字符集

show VARIABLES like \'character%\';
alter database dbt3_s1 character set utf8;
ALTER TABLE lineitem DEFAULT CHARACTER SET utf8;