1、查找以前是否装有mysql

先用：yum remove mysql*命令卸载mysql及相关组件

命令：rpm -qa|grep -i mysql
可以看到如下图的所示：

说明之前安装了：
MySQL-client-5.5.25a-1.rhel5
MySQL-server-5.5.25a-1.rhel5

2、停止mysql服务、删除之前安装的mysql

删除命令：rpm -e ?nodeps 包名
# rpm -ev MySQL-client-5.5.25a-1.rhel5
# rpm -ev MySQL-server-5.5.25a-1.rhel5<??http://www.2cto.com/kf/ware/vc/" target="_blank" class="keylink">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"https://www.cppentry.com/upload_files/article/57/1_37a7b__.jpg" alt="\">

注意：卸载后/etc/my.cnf不会删除，需要进行手工删除
rm -rf /etc/my.cnf

4、再次查找机器是否安装mysql

rpm -qa"grep -i mysql
无结果，说明已经卸载彻底、接下来直接安装mysql即可