//下载mysql rpm包
# wget http://dev.mysql.com/get/mysql57-community-release-el7-11.noarch.rpm

//安装mysql rpm包
# rpm -ivh mysql57-community-release-el7-11.noarch.rpm

//安装mysql
# yum install mysql-community-server

# service mysqld restart

[root@local bin]# grep "password" /var/log/mysqld.log
2017-09-24T08:03:30.664086Z 1 [Note] A temporary password is generated for root@localhost: 8A3xwbk8_P1A

[root@local bin]# mysql -uroot -p
Enter password: 

mysql> SET password=PASSWORD("mysql123");
ERROR 1819 (HY000): Your password does not satisfy the current policy requirements

mysql>grant all privileges on *.* to username@'%' identified by 'password';