MySQL版本：5.7
1、进入home目录：cd /home
2、下载MySQL源安装包：wget http://dev.mysql.com/get/mysql57-community-release-el7-8.noarch.rpm
3、安装MySQL源：yum localinstall mysql57-community-release-el7-8.noarch.rpm
4、检测MySQL源是否安装成功：yum repolist enabled| grep "mysql.*-community.*"
5、安装MySQL：yum install mysql-community-server
6、启动MySQL：systemctl start mysqld 或 service mysqld start
7、检查MySQL启动状态：systemctl status mysqld
8、开机启动：
systemctl enable mysqld
systemctl daemon-reload
9、修改root默认密码：grep 'temporary password' /var/log/mysqld.log
这时他会给你返回一个默认密码：A temporary password is generated for root@localhost: OkS&Kkn+w6qm
登录MySQL：mysql -u root -p
修改密码：ALTER USER 'root'@'localhost' IDENTIFIED BY 'MyNewPass4!';
或者：set password for 'root'@'localhost' =password('你的密码');
通过msyql环境变量可以查看密码策略的相关信息：show variables like '%password%';
/***********************************************************************************/
拓展：下面的操作主要用于navcat外网远程连接上mysql
使用MySQL：use mysql;
flush privileges;
把localhost这条记录的host改为 %； 意思是root可以由任何主机登录mysql，网上很多写法，都没有and host='localhost'这个条件，经常报错：update user set host = '%' where user = 'root' and host= 'localhost';
/***********************************************************************************/
退出MySQL：quit;
10、重启：systemctl restart mysqld 或 service mysqld restart
