Centos下MySql用户管理

1.创建用户

CREATE USER 'username'@'host' IDENTIFIED BY 'password';

2.用户授权

GRANT privileges ON databasename.tablename TO 'username'@'host';

说明: privileges - 用户的操作权限,如SELECT , INSERT , UPDATE 等(详细列表见该文最后面).如果要授予所的权限则使用ALL.;databasename - 数据库名,tablename-表名,如果要授予该用户对所有数据库和表的相应操作权限则可用*表示, 如*.*.

例子:

GRANT SELECT, INSERT ON test.user TO 'pig'@'%';
GRANT ALL ON *.* TO 'pig'@'%';

注意:用以上命令授权的用户不能给其它用户授权,如果想让该用户可以授权,用以下命令:

GRANT privileges ON databasename.tablename TO 'username'@'host' WITH GRANT OPTION;

3.取消授权

REVOKE privilege ON databasename.tablename FROM 'username'@'host';

说明: privilege, databasename, tablename - 同授权部分.

例子:

REVOKE SELECT ON *.* FROM 'pig'@'%';

注意: 假如你在给用户'pig'@'%'授权的时候是这样的(或类似的):GRANT SELECT ON test.user TO 'pig'@'%', 则在使用REVOKE SELECT ON *.* FROM 'pig'@'%';命令并不能撤销该用户对test数据库中user表的SELECT 操作.相反,如果授权使用的是GRANT SELECT ON *.* TO 'pig'@'%';则REVOKE SELECT ON test.user FROM 'pig'@'%';命令也不能撤销该用户对test数据库中user表的Select 权限.

具体信息可以用命令 SHOW GRANTS FOR 'pig'@'%'; 查看.

4.设置或修改密码

SET PASSWORD FOR 'username'@'host' = PASSWORD('newpassword');

如果是当前登陆用户用 SET PASSWORD = PASSWORD("newpassword");

例子:

SET PASSWORD FOR 'pig'@'%' = PASSWORD("123456");

如果忘记root密码，操作如下：

1).linux切换到root用户

2).修改MySql的登陆设置，编辑my.cnf文件

　　 [root@promote /]# vi /etc/my.cnf

　　在[mysqld]字段下加入一句： skip-grant-tables

　　保存退出。

3).重新启动mysqld

　　 [root@promote /]# service mysqld restart

4).之后可以免密码进入MySql，然后use mysql

[root@promote /]# mysql
Welcome to the MySQL monitor.  Commands end with ; or g.
Your MySQL connection id is 3
Server version: 5.7.18 MySQL Community Server (GPL)

Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or 'h' for help. Type 'c' to clear the current input statement.

mysql> use mysql;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed

5).修改root用户密码

mysql> update mysql.user set authentication_string=password('root') where User='root' and Host='localhost';
Query OK, 1 row affected, 1 warning (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 1

6).退出MySql，编辑my.cnf，删除skip-grant-tables一行

7).可用root用户的新密码登进MySql

5.删除用户

DROP USER 'username'@'host';

附表：在MySql中的操作权限

`ALTER`	Allows use of `ALTER TABLE`.
`ALTER ROUTINE`	Alters or drops stored routines.
`CREATE`	Allows use of `CREATE TABLE`.
`CREATE ROUTINE`	Creates stored routines.
`CREATE TEMPORARY TABLE`	Allows use of `CREATE TEMPORARY TABLE`.
`CREATE USER`	Allows use of `CREATE USER`, `DROP USER`, `RENAME USER`, and `REVOKE ALL PRIVILEGES`.
`CREATE VIEW`	Allows use of `CREATE VIEW`.
`DELETE`	Allows use of `DELETE`.
`DROP`	Allows use of `DROP TABLE`.
`EXECUTE`	Allows the user to run stored routines.
`FILE`	Allows use of `SELECT`... `INTO OUTFILE` and `LOAD DATA INFILE`.
`INDEX`	Allows use of `CREATE INDEX` and `DROP INDEX`.
`INSERT`	Allows use of `INSERT`.
`LOCK TABLES`	Allows use of `LOCK TABLES` on tables for which the user also has `SELECT` privileges.
`PROCESS`	Allows use of `SHOW FULL PROCESSLIST`.
`RELOAD`	Allows use of `FLUSH`.
`REPLICATION`	Allows the user to ask where slave or master
`CLIENT`	servers are.
`REPLICATION SLAVE`	Needed for replication slaves.
`SELECT`	Allows use of `SELECT`.
`SHOW DATABASES`	Allows use of `SHOW DATABASES`.
`SHOW VIEW`	Allows use of `SHOW CREATE VIEW`.
`SHUTDOWN`	Allows use of `mysqladmin shutdown`.
`SUPER`	Allows use of `CHANGE MASTER`, `KILL`, `PURGE MASTER LOGS`, and `SET GLOBAL` SQL statements. Allows `mysqladmin debug` command. Allows one extra connection to be made if maximum connections are reached.
`UPDATE`	Allows use of `UPDATE`.
`USAGE`	Allows connection without any specific privileges.