安装5.7版本的mysql无密码设置的情况

一、windows安装mysql5.7数据库密码
管理员身份打开cmd，输入mysql -u root -p回车会直接进入如下：

Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 184
Server version: 5.7.22-log MySQL Community Server (GPL)

Copyright (c) 2000, 2018, 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>

使用mysql数据库，输入：use mysql;

接下来输入：

mysql> update user set authentication_string = password("123456") where user = "root";
Query OK, 0 rows affected, 1 warning (0.00 sec)
Rows matched: 1 Changed: 0 Warnings: 1
mysql> flush privileges; --刷新

这样以后退出数据库，重新输入mysql -u root -p，输入密码就可以进入了。