安裝mysql和mysql-devel都成功，但是安裝mysql-server失敗，如下：
[root@localhost ~]# yum install mysql-server Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile * base: mirrors.sina.cn * extras: mirrors.sina.cn * updates: mirrors.sina.cn No package mysql-server available. Error: Nothing to do
查資料發現是CentOS 7 版本將MySQL數據庫軟件從默認的程序列表中移除，用mariadb代替了
解決辦法：
1. 下載mysql的repo源
$ wget http://repo.mysql.com/mysql-community-release-el7-5.noarch.rpm
2. 安裝mysql-community-release-el7-5.noarch.rpm包
$ rpm -ivh mysql-community-release-el7-5.noarch.rpm
安裝這個包后，會獲得兩個mysql的yum repo源：/etc/yum.repos.d/mysql-community.repo，/etc/yum.repos.d/mysql-community-source.repo。
3. 安裝mysql
$ yum install mysql-server