轉自http://www.cnblogs.com/kerrycode/p/4364465.html中的部分內容
如果是採用二進位制包安裝的MySQL，那麼你用下面命令是找不到任何MySQL元件的。所以如果你不知道MySQL的安裝方式，千萬不要用下面命令來判別是否安裝了MySQL

rpm -qa | grep -i mysql

1、檢查MySQL服務並關閉服務程序

[[email protected] init.d]# ps -ef | grep mysql

root      4752  4302  0 22:55 pts/1    00:00:00 more /etc/init.d/mysql.server
 


root      7176     1  0 23:23 pts/1    00:00:00 /bin/sh /usr/local/mysql/bin/mysqld_safe --datadir=/usr/local/mysql/data --pid-file=/usr/local/mysql/data/DB-Server.localdomain.pid

mysql     7269  7176 15 23:23 pts/1    00:00:01 /usr/local/mysql/bin/mysqld --basedir=/usr/local/mysql --datadir=/usr/local/mysql/data --plugin-dir=/usr/local/mysql/lib/plugin --user=mysql --log-error=/usr/local/mysql/data/DB-Server.localdomain
 
.err --pid-file=/usr/local/mysql/data/DB-Server.localdomain.pid

root      7321  4302  0 23:23 pts/1    00:00:00 grep mysql
[[email protected] init.d]# /etc/init.d/mysql.server statu
MySQL running (7269)[  OK  ]
[[email protected] init.d]# /etc/init.d/mysql.server stop
Shutting down MySQL..[  OK  ]
[[email protected]
 
 init.d]# /etc/init.d/mysql.server status
MySQL is not running[FAILED]
[[email protected] init.d]# 

2.查詢MySQL的安裝目錄並徹底刪除

[root@DB-Server init.d]# whereis mysql
mysql: /usr/local/mysql
[[email protected] init.d]# find / -name mysql
/var/spool/mail/mysql
/usr/local/mysql-5.7.5-m15-linux-glibc2.5-x86_64/include/mysql
/usr/local/mysql-5.7.5-m15-linux-glibc2.5-x86_64/bin/mysql
/usr/local/mysql-5.7.5-m15-linux-glibc2.5-x86_64/data/mysql
/usr/local/mysql
[root@DB-Server init.d]# rm -rf /usr/local/mysql-5.7.5-m15-linux-glibc2.5-x86_64/
[root@DB-Server init.d]# rm -rf /usr/local/
[root@DB-Server init.d]# rm -rf /var/spool/mail/mysql
[root@DB-Server init.d]# 

3、 刪除一些配置檔案

配置檔案一般有/etc/my.cnf 或/etc/init.d/mysql.server，視具體安裝配置情況而定。

4、刪除MySQL使用者以及使用者組

[root@DB-Server ~]# id mysql
uid=101(mysql) gid=501(mysql) groups=501(mysql) context=root:system_r:unconfined_t:SystemLow-SystemHigh
[root@DB-Server ~]# userdel mysql