1.wget https://dev.mysql.com/get/Downloads/MySQL-5.7/mysql-5.7.22-1.el7.x86_64.rpm-bundle.tar
2.按照依赖关系依次安装rpm包 依赖关系依次为common→libs→client→server

rpm -ivh mysql-community-common-5.7.22-1.el7.x86_64.rpm
rpm -ivh mysql-community-libs-5.7.22-1.el7.x86_64.rpm
rpm -ivh mysql-community-client-5.7.22-1.el7.x86_64.rpm
rpm -ivh mysql-community-server-5.7.22-1.el7.x86_64.rpm

安装报错：警告：mysql-community-common-5.7.22-1.el7.x86_64.rpm: 头V3 DSA/SHA1 Signature, 密钥 ID 5072e1f5: NOKEY
解决方法：rpm -ivh mysql-community-common-5.7.22-1.el7.x86_64.rpm --force --nodeps

3.启动

systemctl start mysqld.service    启动mysql
systemctl status mysqld.service  查看mysql状态
systemctl stop mysqld.service   关闭mysql

4.修改密码

查看密码：grep 'temporary password' /var/log/mysqld.log

更改策略，设置 validate_password_policy=0;
mysql> set global validate_password_policy=0;    # 此时，新密码长度大于等于8位才有效，否则报错
修改有效密码长度：

mysql> set global validate_password_length=1;
Query OK, 0 rows affected (0.00 sec)
不管设置  validate_password_length=1,还是2,3,4 ,‘使密码长度生效’这个参数的实际值都是4。超过4后设置是多少实际就是多少。

step2：重设密码：
mysql> set password for root@localhost=password('9527');

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