1、root用户登录到mysql数据库
代码示例:
/usr/local/mysql/bin/mysql -u root -p (输入密码进入mysql)
2、进入mysql，输入：
代码示例:
use mysql;
3、查看user表的情况
代码示例:
SELECT Host,User FROM user;
//指明主机名称，“%”表示匹配所有字符串
4、
代码示例:
UPDATE user SET Host = '%' WHERE User= 'root' LIMIT 1;
5、输入如下命令让刚才设置的命令生效
代码示例:
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
注意，在mysql 命令行形式下一定要输入";"
按照前面五个步骤完成之后，通过控制台输入：
代码示例:
[root@linux ~]# mysql -h localhost -u root -p
Enter password:
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)
不让这么连接数据库

原因：是因为host对应的user字段是空的，我们需要将其改为root即可

代码示例:
mysql> select host,user from user;
+-----------+------+
| host | user |
+-----------+------+
| % | root |
| 127.0.0.1 | root |
| linux | |
| linux | root |
| localhost | |
+-----------+------+
5 rows in set (0.00 sec)

解决办法一：

代码示例:
mysql> update user set user='root' where 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)
解决办法二：
将localhost改为本机的IP地址，则能够识别了。
代码示例:
[root@linux ~]# mysql -h 172.16.42.68 -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 157
Server version: 5.1.66 Source distribution

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