一、查看centos版本

cat /etc/issue

安装mysql5.7

#下载rpm包

wget http://soft.71t.com.cn:81/soft/mysql-5.7.19-1.el6.x86_64.rpm-bundle.tar

#创建mysql目录

mkdir /home/mysql

#解压

tar -xvf mysql-5.7.19-1.el6.x86_64.rpm-bundle.tar -C /home/mysql

#安装numactl和mysql

yum install -y numactl

cd /home/mysql

按以下顺序安装相关rpm：

安装cdh时需要

[root@azkaban mysql]# rpm -ivh mysql-community-common-5.7.19-1.el6.x86_64.rpm --force --nodeps

warning: mysql-community-common-5.7.19-1.el6.x86_64.rpm: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY

Preparing... ########################################### [100%]

1:mysql-community-common ########################################### [100%]

[root@azkaban mysql]# rpm -ivh mysql-community-libs-5.7.19-1.el6.x86_64.rpm --force --nodeps

warning: mysql-community-libs-5.7.19-1.el6.x86_64.rpm: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY

Preparing... ########################################### [100%]

1:mysql-community-libs ########################################### [100%]

[root@slave03 mysql]# rpm -ivh mysql-community-libs-compat-5.7.19-1.el6.x86_64.rpm --force --nodeps

warning: mysql-community-libs-compat-5.7.19-1.el6.x86_64.rpm: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY

Preparing... ########################################### [100%]

1:mysql-community-libs-co########################################### [100%]

[root@azkaban mysql]# rpm -ivh mysql-community-client-5.7.19-1.el6.x86_64.rpm --force --nodeps

warning: mysql-community-client-5.7.19-1.el6.x86_64.rpm: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY

Preparing... ########################################### [100%]

1:mysql-community-client ########################################### [100%]

[root@azkaban mysql]# rpm -ivh mysql-community-server-5.7.19-1.el6.x86_64.rpm --force --nodeps

warning: mysql-community-server-5.7.19-1.el6.x86_64.rpm: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY

Preparing... ########################################### [100%]

1:mysql-community-server ########################################### [100%]

#启动mysql

service mysqld start

#查看默认生成的密码

sudo grep 'temporary password' /var/log/mysqld.log

#登陆mysql

mysql -uroot -p

#第一次重设密码

ALTER USER 'root'@'localhost' IDENTIFIED BY 'MyNewPasswd4!';

#修改host值

mysql>use mysql;

mysql> update user set host = '%' where user ='root';

mysql>flush privileges;

mysql> select host,user from user where user='root';

#修改为简单密码

#只验证密码长度

set global validate_password_policy=0;

mysql>flush privileges;

#查看密码长度

select @@validate_password_length;

修改默认密码的长度(这里修改为6)

set global validate_password_length=6;

mysql>flush privileges;

#重设密码为passwd

ALTER USER 'root'@'%' IDENTIFIED BY 'passwd';

mysql>flush privileges;

exit;

#设置开机自启动

chkconfig mysqld on

#重新用新密码登陆

mysql -uroot -ppasswd

mysql>  Grant all privileges on *.* to 'root'@'%' identified by 'passwd' with grant option;

Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> flush privileges;

Query OK, 0 rows affected (0.00 sec)

centos下完全卸载mysql

yum -y remove mysql-libs-*

使用Yum安装东西时，如果有强制退出过yum或yum异常结束，再下次使用yum命令时会提示：There are unfinished transactions remaining. You might consider running yum-complete-transaction first to finish them。

可以通过以下方法处理：

yum -y install yum-utils

yum clean all

yum-complete-transaction --cleanup-only

一 、yum方式安装的mysql

yum remove mysql mysql-server mysql-libs compat-mysql51

rm -rf /var/lib/mysql

rm /etc/my.cnf

查看是否还有mysql软件：

rpm -qa|grep mysql

如果存在的话，继续删除即可。

二、rpm方式安装的mysql

a)查看系统中是否以rpm包安装的mysql：

[root@azkaban mysql]# rpm -qa | grep -i mysql

mysql-community-libs-5.7.19-1.el6.x86_64

mysql-community-client-5.7.19-1.el6.x86_64

mysql-community-server-5.7.19-1.el6.x86_64

mysql-community-common-5.7.19-1.el6.x86_64

b)依次卸载mysql

[root@azkaban mysql]#rpm -e mysql-community-libs-5.7.19-1.el6.x86_64

[root@azkaban mysql]# rpm -e ...

c)删除mysql服务

[root@azkaban mysql]# chkconfig --list | grep -i mysql

[root@azkaban mysql]# chkconfig --del mysql

d)删除分散mysql文件夹

[root@azkaban mysql]#  whereis mysql

mysql: /usr/lib/mysql   /usr/share/mysql

清空相关mysql的所有目录以及文件

rm -rf /usr/lib/mysql

rm -rf /usr/share/mysql

[root@azkaban mysql]#find / -name mysql

rm -rf  ...

通过以上几步，mysql应该已经完全卸载干净了。