1. 通过wget下载MySql的rpm

[root@VM-4-16-centos ~]# wget https://dev.mysql.com/get/mysql57-community-release-el7-9.noarch.rpm

下载完成后是这样的：

2. 检查是否存在MySql的repo

[root@VM-4-16-centos ~]# cd /etc/yum.repos.d/

[root@VM-4-16-centos yum.repos.d]# ls
CentOS-Base.repo  CentOS-Epel.repo

可以看到没有MySql的repo

3. 安装MySql的repo，并查看是否安装成功

[root@VM-4-16-centos ~]# rpm -ivh mysql57-community-release-el7-9.noarch.rpm 
警告：mysql57-community-release-el7-9.noarch.rpm: 头V3 DSA/SHA1 Signature, 密钥 ID 5072e1f5: NOKEY
准备中...                          ################################# [100%]
正在升级/安装...
   1:mysql57-community-release-el7-9  ################################# [100%]
[root@VM-4-16-centos ~]# cd -
[root@VM-4-16-centos yum.repos.d]# ls
CentOS-Base.repo  CentOS-Epel.repo  mysql-community.repo  mysql-community-source.repo

4. 查看系统原来是否存在MySql包

[root@VM-4-16-centos yum.repos.d]# rpm -qa | grep mysql
mysql57-community-release-el7-9.noarch

可以看到只有我们刚才安装的包，没有其他的mysql包

5. 安装MySql

[root@VM-4-16-centos ~]# yum install -y mysql-server

执行命令后，正常下载即可，但是下载完后会有个告警

失败的软件包是：mysql-community-libs-compat-5.7.37-1.el7.x86_64
 GPG  密钥配置为：file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql

 处理办法：修改 /etc/yum.repos.d/mysql-community.repo，找到你安装的MySql版本。修改其中的gpgcheck=0即可,默认值为1

[root@VM-4-16-centos yum.repos.d]# vim /etc/yum.repos.d/mysql-community.repo

修改前： 

[mysql57-community]
name=MySQL 5.7 Community Server
baseurl=http://repo.mysql.com/yum/mysql-5.7-community/el/7/$basearch/
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql

修改后： 

[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
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql

6. 启动MySql服务并查看启动状态

# 启动mMysql
[root@VM-4-16-centos yum.repos.d]# systemctl start mysqld
# 查看启动状态
[root@VM-4-16-centos ~]# systemctl status mysqld
● mysqld.service - MySQL Server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
   Active: active (running) since 六 2022-03-19 18:56:11 CST; 28min ago
     Docs: man:mysqld(8)
           http://dev.mysql.com/doc/refman/en/using-systemd.html
  Process: 17643 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid $MYSQLD_OPTS (code=exited, status=0/SUCCESS)
  Process: 17579 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=0/SUCCESS)
 Main PID: 17647 (mysqld)
   CGroup: /system.slice/mysqld.service
           └─17647 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid

3月 19 18:56:06 VM-4-16-centos systemd[1]: Starting MySQL Server...
3月 19 18:56:11 VM-4-16-centos systemd[1]: Started MySQL Server.

runing表示已经启动

7. 查看MySql的版本号

[root@VM-4-16-centos ~]# mysql -V
mysql  Ver 14.14 Distrib 5.7.37, for Linux (x86_64) using  EditLine wrapper

8. 查看MySql初始密码

[root@VM-4-16-centos ~]# vim /etc/my.cnf

通过my.cnf文件找到log-error=/var/log/mysqld.log文件，在改文件中根据password关键字查询初始密码

[root@VM-4-16-centos ~]# grep "password" /var/log/mysqld.log

找到初始密码之后，就可以开始登录了

9. 登录MySql

[root@VM-4-16-centos ~]# mysql -uroot -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.7.37

Copyright (c) 2000, 2022, 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>

Enter password: 这里输入密码即可，出现mysql>表示已经登录成功

10. 修改登录密码

mysql> alter user 'root'@'localhost' identified by "xxxxxx";

xxxxxx表示需要修改的密码

11. 开放连接权限

mysql> GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY 'xxxxxx' WITH GRANT OPTION;

xxxxxx是指root的密码

以上就是centos7.6安装MySql5.7+的步骤