安装mysql
1.下载mysql源安装包
shell> wget /get/mysql57-community-release-el7-8.noarch.rpm
2.安装mysql源
shell> yum localinstall mysql57-community-release-el7-8.noarch.rpm
3.检查mysql源是否安装成功
shell> yum repolist enabled | grep "mysql.*-community.*"
4.修改 vim /etc/yum.repos.d/mysql-community.repo源 ，改变默认安装的mysql版本。比如要安装5.6版本，将5.7源的enabled=1改成enabled=0。然后再将5.6源的enabled=0改成enabled=1即可。
vim /etc/yum.repos.d/mysql-community.repo
5.安装MySQL
shell> yum install mysql-community-server
6.启动MySQL服务
shell> systemctl start mysqld
7.开机启动
shell> systemctl enable mysqld
shell> systemctl daemon-reload
8.修改root本地登录密码
1)查看mysql密码
shell> grep 'temporary password' /var/log/mysqld.log
2)连接mysql
shell> mysql -uroot -p
3)修改密码[注意：后面的分号一定要跟上]
mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'MyNewPass4!';
或者：
mysql> set password for 'root'@'localhost'=password('MyNewPass4!');
mysql> show variables like ‘%password%’;
9.添加远程登录用户
mysql> GRANT ALL PRIVILEGES ON *.* TO 'caoxiaobo'@'%' IDENTIFIED BY 'Caoxiaobo0917!' WITH GRANT OPTION;
10.设置密码安全规则
set global validate_password_policy=0;
set global validate_password_length=1;
11.刷新映射关系
flush privileges;
卸载mysql
yum方式安装的mysql
1、yum remove mysql mysql-server mysql-libs compat-mysql51
2、rm -rf /var/lib/mysql
3、rm /etc/f
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。
rpm方式安装的mysql
a)查看系统中是否以rpm包安装的mysql：
[root@localhost opt]# rpm -qa | grep -i mysql
MySQL-server-5.6.17-1.el6.i686
MySQL-client-5.6.17-1.el6.i686
b)卸载mysql
[root@localhost local]# rpm -e MySQL-server-5.6.17-1.el6.i686
[root@localhost local]# rpm -e MySQL-client-5.6.17-1.el6.i686
c)删除mysql服务
[root@localhost local]# chkconfig –list | grep -i mysql
[root@localhost local]# chkconfig –del mysql
d)删除分散mysql文件夹
[root@localhost local]# whereis mysql 或者 find / -name 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
rm -rf /usr/f
