MySQL8.0降级为MySQL5.7

OS：centos 7.6

 

注：更换之前需做好数据库文件的备份

 

一、卸载MySQL8.0

rpm -qa | grep -i mysql
yum -y remove mysql80-community-release-el7-1.noarch
yum -y remove mysql-community-server-8.0.20-1.el7.x86_64
yum -y remove mysql-community-common-8.0.20-1.el7.x86_64

二、安装MySQL5.7

  1.下载最新的源码： 

       官网地址  https://dev.mysql.com/downloads/repo/yum/

 

wget https://dev.mysql.com/get/mysql80-community-release-el7-1.noarch.rpm

2.安装源码

rpm -Uvh mysql80-community-release-el7-1.noarch.rpm

3.查看所有MySQL包

yum repolist all | grep mysql

4.禁用MySQL8.0版本，启用MySQL5.7版本

yum -y install yum-utils   #安装yum管理工具，系统默认不安装
yum-config-manager --disable mysql80-community
yum-config-manager --enable mysql57-community

  当enabled=1时，是启用的；当enabled=0时，是禁用的。也可以进入/etc/yum.repos.d/mysql-community.repo 进行修改设置

5.检查现在可用版本

 yum repolist enabled | grep mysql

6.等待安装

yum install mysql-community-server
mysql --version

7.开启服务

systemctl start mysqld
systemctl enable mysqld

 注：若开启失败，需在/var/lib/mysql下新建data目录，并修改/etc/my.cnf文件对应配置“ datadir=/var/lib/mysql/data”,再次尝试开启服务

三、启动后配置

1.更改MySQL密码

grep 'temporary password' /var/log/mysqld.log
mysql -u root -p'初始密码'
ALTER USER 'root'@'localhost' IDENTIFIED BY '123456';

2.允许root用户远程连接

use  mysql;
select host, user, authentication_string, plugin from user;
update user set host = "%" where user = "root";
flush privileges;

测试连接并导入已备份数据库

参考文档：

https://www.cnblogs.com/littlemonsterksn/p/10154662.html

https://blog.csdn.net/jjddrushi/article/details/83827945

https://blog.csdn.net/toooooop8/article/details/103851738( MySQL导入数据库版本不兼容处理方法)