关于mysql授权账号权限时的空密码问题

-root ~]$ mysql -uroot -p

Enter password:
ERROR 1045 (28000): Access denied for user ‘root’@'localhost’ (using password: NO)
[ruifengyun@bj-root ~]$ mysql -uroot -p

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
mysql> update user set password=password(’123123′) where user=’root’;
Query OK, 0 rows affected (0.02 sec)
Rows matched: 1  Changed: 0  Warnings: 0

mysql> SHOW GRANTS FOR root\G
*************************** 1. row ***************************
Grants for root@%: GRANT USAGE ON *.* TO ‘root’@'%’ IDENTIFIED BY PASSWORD ‘*E56A114692FE0DE073F9A1DD68A00EEB9703F3F1′
*************************** 2. row ***************************
Grants for root@%: GRANT ALL PRIVILEGES ON root_master.* TO ‘root’@'%’
2 rows in set (0.00

mysql> select user,host,password from mysql.user order by user,host;
+————-+—————+——————————————-+
| user        | host          | password                                  |
+————-+—————+——————————————-+
|             | bj-root |                                           |
|             | localhost     |                                           |
| root        | %             | *E56A114692FE0DE073F9A1DD68A00EEB9703F3F1 |
| root        | 127.0.0.1     | *B335B8949A6AF011EA3D9F37F046C6E413BC23FB |
| root        | ::1           |                                           |
| root        | bj-root |                                           |
| root        | localhost     | *B335B8949A6AF011EA3D9F37F046C6E413BC23FB |
| weixin_user | %             | *DF81D3DE3ABC1508BFB0F1D4DE9C2EECBAE43E4F |
| weixinuser  | %             | *DF81D3DE3ABC1508BFB0F1D4DE9C2EECBAE43E4F |
+————-+—————+——————————————-+
9 rows in set (0.00 sec)

解决方法,删除为空的用户授权:

mysql>
mysql>
mysql> drop user ”@’localhost’;
Query OK, 0 rows affected (0.04 sec)

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

mysql> drop user ”@’bj-root′;
Query OK, 0 rows affected (0.00 sec)

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

mysql>
mysql> select user,host,password from mysql.user order by user,host;
+————-+—————+——————————————-+
| user        | host          | password                                  |
+————-+—————+——————————————-+
| admin       | %             |                                           |
| root        | %             | *E56A114692FE0DE073F9A1DD68A00EEB9703F3F1 |
| root        | 127.0.0.1     | *B335B8949A6AF011EA3D9F37F046C6E413BC23FB |
| root        | ::1           |                                           |
| root        | bj-root |                                           |
| root        | localhost     | *B335B8949A6AF011EA3D9F37F046C6E413BC23FB |
| weixin_user | %             | *DF81D3DE3ABC1508BFB0F1D4DE9C2EECBAE43E4F |
| weixinuser  | %             | *DF81D3DE3ABC1508BFB0F1D4DE9C2EECBAE43E4F |
+————-+—————+——————————————-+
8 rows in set (0.00 sec)

原因是因为有mysql库的user表有空值的情况mysql进行认证的时候，匹配都了空值，所以就直接能进入myql里面了。