mysql数据库常见报错解决办法

以centos7系统为例

报错ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)解决办法

新装的mysql数据库没有登陆密码，这种错误常出现在这个时候

解决办法是跳过MySQL的密码认证过程，方法如下：

vim /etc/my.cnf

在打开的文档中的[mysqld]字段后边添加

skip-grant-tables

保存退出
重启mysql服务

~]# systemctl restart mysqld.service
~]# service mysqld restart

输入命令

mysql -u root -p

密码直接回车即可

修改密码

mysql> use mysql;
mysql> update user set password=password("******") where user="root";
mysql> flush privileges;  # 使修改密码立刻生效
mysql> quit

可能会报错ERROR 1054 (42S22): Unknown column 'password' in 'field list'，解决办法如下

报错ERROR 1054 (42S22): Unknown column 'password' in 'field list'解决办法

出现这种问题使原因是 5.7版本下的mysql数据库下已经没有password这个字段了，password字段改成了authentication_string

mysql> update mysql.user set authentication_string=password('******') where user='root';  #修改密码成功
Query OK, 1 row affected, 1 warning (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 1

mysql> flush privileges;  #立即生效
Query OK, 0 rows affected (0.00 sec)

mysql> quit
Bye

正常登陆即可，如果报错ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.，解决办法如下

报错ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.的解决办法

--------------------
mysql8用这两句：
set global validate_password.policy=0;
set global validate_password.length=1;
--------------------
mysql> set global validate_password_policy=0;
Query OK, 0 rows affected (0.00 sec)

mysql> alter user 'root'@'localhost' identified by '******';
Query OK, 0 rows affected (0.00 sec)

--------------------
mysql8用这句
ALTER USER ‘root’@‘localhost’ IDENTIFIED BY ‘new pwd’
--------------------

mysql> quit
Bye
[root@xxx ~]# mysql -u root -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 6
Server version: 5.7.28 MySQL Community Server (GPL)

Copyright (c) 2000, 2019, 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> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
4 rows in set (0.00 sec)

mysql>