1.通過https://mirrors.tuna.tsinghua.edu.cn鏡像源安裝了MySQL5.7.22
rpm -ivh --force --nodeps https://mirrors.tuna.tsinghua.edu.cn/mysql/yum/mysql57-community-el7/mysql-community-client-5.7.22-1.el7.x86_64.rpm
rpm -ivh --force --nodeps https://mirrors.tuna.tsinghua.edu.cn/mysql/yum/mysql57-community-el7/mysql-community-server-5.7.22-1.el7.x86_64.rpm
2.通過/etc/my.cnf配置文件找到MySQL的錯誤日志存在/var/log/mysql.log里，在該日志里查找到mysql的root用戶的臨時登錄密碼
[root@ip-172-31-34-225 log]# cat /var/log/mysqld.log | grep 'temporary password'
2019-02-13T10:32:25.917190Z 1 [Note] A temporary password is generated for root@localhost: a1+J)%zhEURa
3.用臨時密碼通過命令行登錄報錯：ERROR 1045 (28000): Unknown error 1045
4.原因是密碼錯誤,參考鏈接https://blog.csdn.net/nicolelili1/article/details/78833667（為什么初始的臨時密碼是錯誤的？這個還沒弄明白）
vim /etc/my.cnf
skip-grant-tasbles #添加本行內容，意思是跳過授權表實現免密登錄
5.systemctl restart mysqld
6.在命令行輸入mysql回車即可登錄，登錄后設置新的root密碼，下次通過新的密碼即可登錄
mysql> update user set authentication_string = password('XXXXXX') where user = 'root';
Query OK, 1 row affected, 1 warning (0.00 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
7.vim /etc/my.cnf
#skip-grant-tables #為提高安全性，將該行注釋然后重啟mysql.