首先要确保之前安装的mysql被卸载干净
[root@localhost ~]# rpm -qa|grep -i mysql
mysql-community-release-el7-5.noarch
[root@localhost ~]# rpm -e mysql-community-release-el7-5.noarch --nodeps
或者
[root@localhost ~]# yum -y remove mysql-libs*
然后登陆mysql官网，找到对应版本的yum源地址：
登陆官网：http://dev.mysql.com/downloads/repo/yum/
点击对应版本后面的Download按钮，进入到下面这个页面：
通过鼠标右键，选择：复制链接地址，就可以获得对应版本的yum源地址，例如：
http://dev.mysql.com/get/mysql57-community-release-el6-9.noarch.rpm
通过以下步骤进行安装：
[root@localhost ~]# rpm -Uvh http://dev.mysql.com/get/mysql57-community-release-el6-9.noarch.rpm
Retrieving http://dev.mysql.com/get/mysql57-community-release-el6-9.noarch.rpm
warning: /var/tmp/rpm-tmp.q1TNuY: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY
Preparing... ########################################### [100%]
1:mysql57-community-relea########################################### [100%]
[root@localhost ~]# yum repolist enabled | grep mysql
Failed to set locale, defaulting to C
mysql-connectors-community MySQL Connectors Community 21
mysql-tools-community MySQL Tools Community 38
mysql57-community MySQL 5.7 Community Server 114
[root@localhost ~]# yum install mysql-community-server
查看mysql root缺省密码
[root@localhost ~]# sudo grep 'temporary password' /var/log/mysqld.log
2016-08-11T10:16:43.180993Z 1 [Note] A temporary password is generated for root@localhost: 4k#Xq3h4Q7kR