1. 检测系统是否已安装 mysql
   [root@localhost ~]# yum list installed | grep mysql
2. 删除系统已安装的 mysql 及其依赖
   [root@localhost ~]# yum -y remove mysql-libs.i686
3. 给CentOS添加rpm源
   wget
   4.安装yum源
   [root@localhost ~]# yum install mysql-community-release-el6-5.noarch.rpm
   [root@localhost ~]# yum repolist all | grep mysql
   [root@localhost ~]# yum repolist all | grep mysql
   [root@localhost ~]# yum-config-manager --disable mysql55-community
   [root@localhost ~]# yum-config-manager --disable mysql56-community
   [root@localhost ~]# yum-config-manager --enable mysql57-community-dmr
4. 安装 MySQL 服务端
   [root@localhost ~]#yum install mysql-community-server
   Dependency Installed:
   mysql-community-client.x86_64 0:5.7.22-1.el6
   mysql-community-common.x86_64 0:5.7.22-1.el6
   mysql-community-libs.x86_64 0:5.7.22-1.el6

Complete!

6. 启动 mysql 服务
   [root@localhost ~]# service mysqld start
   查看启动是否成功：
   [root@localhost ~]# service mysqld status
   mysqld (pid 10698) 正在运行...
7. 修改 root 初始密码
   我这里用的是安全模式下进入设置密码
   [root@localhost ~]#service mysqld stop
   [root@localhost ~]#mysqld_safe –skip-grant-tables &
   重新开一个终端输入一下命令，然后直接敲enterj键：
   [root@localhost ~]#mysql -uroot -p
   进入之后，敲use mysql,用mysql数据库;
   修改root用户密码
   mysql> update user set authentication_string=password(123456) where user='root';
   注：mysql5.7的密码字段是authentication_string，不是password
   刷新权限并退出
   mysql> >flush privileges;
   mysql> >quit
   重启mysql，用密码123456即可登录mysql
   [root@localhost ~]# service mysqld restart
   [root@localhost ~]# mysql -u root -p
   Oracle is a registered trademark of Oracle Corporation and/or its
   affiliates. Other names may be trademarks of their respective
   owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql>

8. 设置mysql开机启动
   [root@localhost ~]# chkconfig mysqld on
   [root@localhost ~]# chkconfig mysqld status