1. 下载mysql源安装包(https://dev.mysql.com/downloads/mysql/5.7.html#downloads):
# wget https://dev.mysql.com/get/Downloads/MySQL-5.7/mysql-community-server-5.7.22-1.el7.x86_64.rpm
  
2. 安装mysql源:
# yum localinstall mysql-community-server-5.7.22-1.el7.x86_64.rpm
  
3. 检查源是否安装成功:
# yum repolist enabled | grep "mysql.*-community.*"
  
4. 检查源安装配置文件是否正确:
# vim /etc/yum.repos.d/mysql-community.repo
将5.7源enabled=1(检查是否正确)
  
5. 安装mysql:
# yum install mysql-community-server
  
6. 启动mysql服务:
# systemctl start mysqld
7. 可以选择开机启动(可选)
# systemctl enable mysqld
# systemctl daemon-reload
8. 停止服务:
# systemctl stop mysqld.service
9. 修改配置文件:
# vi /etc/my.cnf
在[mysqld]中添加skip-grant-tables(一般加在最后,免密登陆)
10. 启动服务:
# systemctl start mysqld.service
11. # mysql -uroot -p 直接Enter登入
12. 先执行use mysql,指定mysql数据库为当前库
13. 修改密码:update mysql.user set authentication_string=password(‘nriet123‘) where user=‘root‘ and Host =‘localhost‘;
14. 停止服务,修改配置文件(去掉skip-grant-tables),启动服务(禁用免密登录)
15 远程客户端(Navicat或者SQLyog)连接需要执行下列语句:
mysql> GRANT ALL PRIVILEGES ON *.* TO ‘root‘@‘%‘ IDENTIFIED BY ‘nriet123‘ WITH GRANT OPTION;
Query OK, 0 rows affected (0.00 sec)
   如果出现错误 ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.
	  原因:Mysql 密码安全策略: validate_password_policy
	  解决:
		  这个与validate_password_policy的值有关。
		  validate_password_policy有以下取值:
			  0 or LOW
				  长度
			  1 or MEDIUM
				  长度;数字、小写/大写和特殊字符
			  2 or STRONG
				  长度;数字、小写/大写和特殊字符;字典文件
			
	  1. set global validate_password_policy=0; 
		  更改密码长度:密码最小长度为4(设置 1、2、3、4,最低长度都是 4。)
			  set global validate_password_length=4;
			
		  查看密码validate:
			  SHOW VARIABLES LIKE ‘validate_password%‘;
			
	  2. 修改成简单密码:alter user ‘root‘@‘localhost‘ identified by ‘nriet123‘;
16 . mysql> FLUSH PRIVILEGES;
         Query OK, 0 rows affected (0.00 sec)
原文:https://www.cnblogs.com/changlezhong/p/9280718.html