1、删除不用的账户
(1) 查看当前已存在账户
mysql> select user,host,password from mysql.user; 或下面的命令
#mysql> sELECT DISTINCT CONCAT('User: ''',user,'''@''',host,''';') AS query FROM mysql.user;
+---------------------------------------+
| query |
+---------------------------------------+
| User: 'root'@'127.0.0.1'; | #不要删
| User: 'wenqiang'@'172.16.1.%'; |
| User: 'root'@'localhost'; | #不要删
| User: 'root'@'localhost.localdomain'; |
+---------------------------------------+
4 rows in set (0.00 sec)mysql> drop user wenqiang@'172.16.1.%'; #删除不需要的用户(2) 授权用户时尽量不要使用%(该符号表示用户可以从任何地方都可以登陆)
授权格式：grant 权限 on 数据库.* to 用户名@用户所在网段 identified by "密码";
#只允许root用户从10.0.0.10登陆mysql并授予全库访问权限，同时为root用户设置密码123456
mysql> grant all on *.* to root@'10.0.0.10' identified by '123456'; #这种情况是只授权，root用户可以使用空密码从本地登录
mysql> grant all on *.* to root@'localhost';#这种情况是root用户可以从本地登录，同时设置密码abc123（root用户可以设置多套登录密码）
mysql> grant all on *.* to root@'localhost' identified by 'abc123';
3、如果不小心把’root’@‘localhost’; 的授权删掉，应该这样解决
(1)这样登陆上去，并增加一条localhost的权限
[root@localhost ~]# mysql -uroot -p -h 127.0.0.1 #通过127.0.0.1登录上去
mysql> grant all on *.* to root@'localhost' identified by 'abc123'; #在增加一条localhost的授权
mysql> flush privileges;新增加的root用户可能没有最高权限，见第3.1
3.1、当root用户无法给普通用户授权的时候
(1)登录mysql
[root@localhost ~]# mysql -uroot -p -h localhost
mysql> grant all on *.* to root@'localhost' identified by '123456';
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES) #报错(2)查看当前有哪些用户
mysql> SELECT DISTINCT CONCAT('User: ''',user,'''@''',host,''';') AS query FROM mysql.user;
+---------------------------------------+
| query |
+---------------------------------------+
| User: 'root'@'127.0.0.1'; | #使用 mysql -uroot -p -h127.0.0.1登录mysql授权没问题
| User: 'wenqiang'@'172.16.1.%'; |
| User: 'root'@'localhost'; | #我发现从localhost登录的root用户无法给普通用户授权
| User: 'root'@'localhost.localdomain'; |
+---------------------------------------+
4 rows in set (0.00 sec)(3)查看该root用户的Grant_priv选项是Y还是N(N表示无权给普通用户授权)
mysql> select * from mysql.user where User='root' and Host='localhost'\G;
*************************** 1. row ***************************Host: localhostUser: rootPassword: *6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9Select_priv: YInsert_priv: YUpdate_priv: YDelete_priv: YCreate_priv: YDrop_priv: YReload_priv: YShutdown_priv: YProcess_priv: YFile_priv: YGrant_priv: N #无授权权限References_priv: YIndex_priv: YAlter_priv: YShow_db_priv: YSuper_priv: YCreate_tmp_table_priv: YLock_tables_priv: YExecute_priv: YRepl_slave_priv: YRepl_client_priv: YCreate_view_priv: YShow_view_priv: YCreate_routine_priv: YAlter_routine_priv: YCreate_user_priv: YEvent_priv: YTrigger_priv: Y
Create_tablespace_priv: Yssl_type: ssl_cipher: x509_issuer: x509_subject: max_questions: 0max_updates: 0max_connections: 0max_user_connections: 0plugin: mysql_native_passwordauthentication_string: password_expired: N
1 row in set (0.00 sec)ERROR:
No query specified(3)把Grant_priv选项的N改为Y就可以了
mysql> update mysql.user set Grant_priv='Y' where User='root' and Host='localhost';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)(4)退出重新登录mysql，再次给普通用户授权(一定要先退出mysql)
mysql> grant all on *.* to root@'localhost' identified by '123456';
Query OK, 0 rows affected (0.00 sec)
