亲测有效：centos8安装mysql5.7

前言

由于MySQL版本不兼容原因，你需要安装MySQL5.7，而不是安装MySQL8，那么你就麻烦了，Centos8默认是安装MySQL8的，因为Centos8的AppStream仓库只包含MySQL8的包，如果你在百度搜的方法不行，那么可以尝试一下我的办法在centos8中安装mysql5.7服务器。演示步骤如下：

演示

步骤1：添加MySQL5.7仓库

关闭Centos8中MySQL默认的AppStream仓库：

sudo dnf remove @mysql
sudo dnf module reset mysql && sudo dnf module disable mysql

目前还没有EL8版本的MySQL仓库，所以我们这里用EL7的代替，创建一个新的仓库文件：

sudo vi /etc/yum.repos.d/mysql-community.repo

然后将以下内容粘贴到新建的仓库文件中：

[mysql57-community]
name=MySQL 5.7 Community Server
baseurl=http://repo.mysql.com/yum/mysql-5.7-community/el/7/$basearch/
enabled=1
gpgcheck=0

[mysql-connectors-community]
name=MySQL Connectors Community
baseurl=http://repo.mysql.com/yum/mysql-connectors-community/el/7/$basearch/
enabled=1
gpgcheck=0

[mysql-tools-community]
name=MySQL Tools Community
baseurl=http://repo.mysql.com/yum/mysql-tools-community/el/7/$basearch/
enabled=1
gpgcheck=0

步骤2：开始安装MySQL5.7

但步骤1的仓库文件创建完成后，就可以通过以下的命令在centos8中安装MySQL5.7了：

sudo dnf --enablerepo=mysql57-community install mysql-community-server

输入Y开始安装

步骤3：自动启动和安全配置

但第一次安装好MySQL5.7后，需要开启服务，实现重启自动启动：

sudo systemctl enable --now mysqld.service

然后获取mysql初始密码，用于后续安装配置操作

grep 'A temporary password' /var/log/mysqld.log |tail -1

接着开始对mysql进行安全配置，通过MySQL Secure Installation去修改密码、关闭root远程登陆权限,、删除匿名用户、删除测试数据库等：

sudo mysql_secure_installation
Securing the MySQL server deployment.
Enter password for user root:

输入刚才获取的初始密码，开始配置：

Change the password for root ? ((Press y|Y for Yes, any other key for No) : Yes

New password: 
Re-enter new password: 

Estimated strength of the password: 100 
Do you wish to continue with the password provided?: Yes

Remove anonymous users?: Yes
Success.

Disallow root login remotely? : Yes
Success.

Remove test database and access to it? : Yes
 - Dropping test database...
Success.
 - Removing privileges on test database...
Success.

Reload privilege tables now? (Press y|Y for Yes) : Yes
Success.

All done!

届时，就可以使用MySQL命令行工具操作数据库了

操作

测试数据库连接

$ mysql -u root -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 15
Server version: 5.7.28 MySQL Community Server (GPL)

Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.

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> SELECT VERSION();
+-----------+
| VERSION() |
+-----------+
| 5.7.28    |
+-----------+
1 row in set (0.00 sec)

mysql> QUIT
Bye

测试创建数据库和用户

mysql> CREATE DATABASE test_db;
Query OK, 1 row affected (0.09 sec)

mysql> CREATE USER 'test_user'@'localhost' IDENTIFIED BY "Strong34S;#";
Query OK, 0 rows affected (0.04 sec)

mysql> GRANT ALL PRIVILEGES ON test_db.* TO 'test_user'@'localhost';
Query OK, 0 rows affected (0.02 sec)

mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.02 sec)

测试删除数据库

mysql> DROP DATABASE test_db;
Query OK, 0 rows affected (0.14 sec)

mysql> DROP USER 'test_user'@'localhost';
Query OK, 0 rows affected (0.11 sec)

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
4 rows in set (0.01 sec)

mysql> QUIT
Bye

额外：防火墙配置

允许远程3306端口连接

sudo firewall-cmd --add-service=mysql --permanent
sudo firewall-cmd --reload

添加可信网络

sudo firewall-cmd --permanent --add-rich-rule 'rule family="ipv4" \
service name="mysql" source address="10.10.10.0/24" accept'