进入mysql官网https://www.mysql.com/cn/downloads/
yum安装步骤
清理环境
[root@localhost~]# yum -y erase $(rpm -qa | grep -E “mysql|mariadb”)
[root@localhost ~]# userdel -r mysql
[root@localhost ~]# rm -rf /etc/my*
[root@localhost ~]# rm -rf /var/lib/mysql
下载yum源的rpm安装包
[root@localhost ~]# yum install -y https://dev.mysql.com/get/mysql80-community-release-el7-7.noarch.rpm
[root@localhost ~]# vim /etc/yum.repos.d/mysql-community.repo
把安装5.7的源打开, 关闭安装8.0的源
enabled=0关闭源 enabled=1打开源
第二种修改的方法，方便脚本修改
[root@localhost ~]# yum-config-manager –disable mysql80-community
[root@localhost ~]# yum-config-manager –enable mysql57-community
临时关闭，如果要永久关闭，请参考前两种
yum install -y mysql-community-server –enablerepo mysql57-community –disablerepo mysql80-community
关闭防火墙和selinux
[root@localhost ~]# sed -ri s/SELINUX=enforcing/SELINUX=disabled/g /etc/selinux/config && setenforce 0
[root@localhost ~]# systemctl stop firewalld && systemctl disable firewalld
安装必要的软件包
[root@localhost ~]# yum -y install mysql-community-server
[root@localhost ~]# systemctl start mysqld
从日志中找出密码（有可能没有密码）
[root@localhost ~]# grep “password” /var/log/mysqld.log
2023-10-25T12:18:15.104207Z 1 [Note] A temporary password is generated for root@localhost: &/sF*A(G3n2#
[root@localhost ~]# mysql -uroot -p”&/sF*A(G3n2#”
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.44
Copyright (c) 2000, 2023, Oracle and/or its affiliates.
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> \q
Bye
修改mysql数据库密码
mysqladmin -uroot -p’&/sF*A(G3n2#’ password “new_passwd”
yum安装mysql不支持修改弱密码，如需要修改弱密码需要进入MySQL配置文件添加：
[root@localhost~]# vim /etc/my.cnf
关闭mysql密码强度策略，生产环境切勿尝试，首次启动不可关闭
validate-password=OFF
如果忘记数据库密码，需要进入mysql配置文件添加：
#跳过密码登录数据库
skip-grant-tables
以上两个参数不可同时存在
然后登入mysql数据库设置密码
update mysql.user set authentication_string=password(“new_passwd”) where User=’root’ and Host=”localhost”;
更新密码后需要进入数据库删除mysql配置文件里跳过密码skip-grant-tables。
注意：每次修改mysql配置文件后都要重启mysqld服务才可以。