yum 方式卸载MySQL与安装MySQL 1、 rpm -qa | grep -i mysql命令查看已经安装过的组件    [root@VM_0_10_centos ~]# rpm -qa | grep -i mysql 下面是显示安装过的组件        mysql-community-common-5.7.24-1.el7.x86_64        mysql-community-devel-5.7.24-1.el7.x86_64        mysql57-community-release-el7-10.noarch        mysql-community-libs-5.7.24-1.el7.x86_64        mysql-community-libs-compat-5.7.24-1.el7.x86_64        mysql-community-server-5.7.24-1.el7.x86_64        mysql-community-client-5.7.24-1.el7.x86_642、 使用 yum -y remove mysql-community-common-5.7.24-1.el7.x86_64删除3、 rpm -qa | grep -i mysql查看还有什么组件4、 有什么组件就用 yum -y remove删除什么5、 用whereis mysql 查看目录 /usr/share/mysql6、 删除目录 #rm -rf /usr/share/mysql7、 # yum -y install https://dev.mysql.com/get/mysql57-community-release-el7-11.noarch.rpm  //设置yum源为mysql8、 #yum install -y mysql-server  //安装mysql服务9、 #yum repolist //查看是否安装10、#systemctl start mysqld //启动mysql11、#ps aux | grep mysqld  //查看是否启动12、#systemctl enable mysqld  //设置开机自动启动13、#cat /var/log/mysqld.log |grep 'A temporary password'  //查看root随机密码14、#mysql -u 'root' -p '输入临时密码'  // 进入MySQL15、#alter user 'root'@'localhost' identified by 'HgY1234.?'; //修改root密码 先修改成为一个复杂一点的才能进去     (set global validate_password_policy=0;) //设置简单密码    (select @@validate_password_length;) //查看密码要求的长度    (set global validate_password_length=1;) //修改密码要求的长度16、#alter user 'root'@'localhost' identified by '12345678'; //修改密码17、#use mysql;18、#select host, user from user;   //查看远程连接权限19、#update user set host = '%' where user = 'root' and host='localhost'; //开发root远程连接权限20、#flush privileges;    //刷新权限