[root@localhost 桌面]# ps -ef|grep mysql
mysql 2688 1 0 13:31 ? 00:00:00 /bin/sh /usr/bin/mysqld_safe --basedir=/usr
mysql 2857 2688 0 13:31 ? 00:00:01 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib64/mysql/plugin --log-error=/var/log/mysqld.log --pid-file=/var/run/mysqld/mysqld.pid --socket=/var/lib/mysql/mysql.sock
root 4326 4294 0 13:39 pts/0 00:00:00 grep --color=auto mysql/

[root@localhost 桌面]# rpm -qa | grep mysql
mysql-community-libs-5.6.36-2.el7.x86_64
mysql-community-release-el7-5.noarch
mysql-community-server-5.6.36-2.el7.x86_64
mysql-community-client-5.6.36-2.el7.x86_64
mysql-community-devel-5.6.36-2.el7.x86_64
mysql-community-common-5.6.36-2.el7.x86_64

[root@localhost 桌面]#  service mysqld start
Redirecting to /bin/systemctl start  mysqld.service

[root@localhost 桌面]# service mysqld start mysqld:未被识别的服务

#列出所有被安装的rpm package
rpm -qa | grep mariadb#卸载
rpm -e mariadb-libs-5.5.37-1.el7_0.x86_64

[root@localhost 桌面]# rpm -ivh '/home/xuxiaoyu/桌面/mysql-community-release-el7-5.noarch.rpm'  (回车)

　准备中... ################################# [100%]
　软件包 mysql-community-release-el7-5.noarch 已经安装

[root@localhost 桌面]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.6.36 MySQL Community Server (GPL)Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.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>