准备安装环境

[root@server2 ~]# cat /etc/redhat-release 
CentOS Linux release 7.4.1708 (Core) 
[root@server2 ~]# uname -r
3.10.0-693.el7.x86_64

查询已安装的旧版本mysql

rpm -qa | grep mysql
rpm -qa | grep mariadb

卸载已安装的旧版本mysql

rpm -e --nodeps {file_name}
# {file_name} 是查询到的程序名

选择合适的版本

网址：https://downloads.mysql.com/archives/community/

需要安装wget程序

yum install -y wget

下载安装文件

下载地址：https://downloads.mysql.com/archives/get/p/23/file/mysql-5.7.30-1.el7.x86_64.rpm-bundle.tar

[root@server2 ~]# wget https://downloads.mysql.com/archives/get/p/23/file/mysql-5.7.30-1.el7.x86_64.rpm-bundle.tar

解压缩下载文件

[root@server2 ~]# tar -xvf mysql-5.7.30-1.el7.x86_64.rpm-bundle.tar 

安装perl依赖包

yum install -y perl

安装mysql

安装顺序：common→libs→client→server

rpm -ivh mysql-community-common-5.7.30-1.el7.x86_64.rpm
rpm -ivh mysql-community-libs-5.7.30-1.el7.x86_64.rpm
rpm -ivh mysql-community-client-5.7.30-1.el7.x86_64.rpm
rpm -ivh mysql-community-server-5.7.30-1.el7.x86_64.rpm

启动mysql

systemctl start mysqld

检查进程与服务端口号

[root@server2 ~]# ps -ef | grep mysqld
mysql      1199      1  0 06:09 ?        00:00:00 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid

[root@server2 ~]# netstat -lntup | grep mysqld
tcp6       0      0 :::3306                 :::*                    LISTEN      1199/mysqld         

获取初始化root密码

grep 'temporary password' /var/log/mysqld.log

[root@server2 ~]# grep 'temporary password' /var/log/mysqld.log
2021-09-09T22:09:29.134740Z 1 [Note] A temporary password is generated for root@localhost: 4=4kaOLqkgtl

使用初始密码登录mysql

mysql -u root -p'4=4kaOLqkgtl'

[root@server2 ~]# mysql -u root -p'4=4kaOLqkgtl'
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 3
Server version: 5.7.30

Copyright (c) 2000, 2020, 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> 

修改密码策略

set global validate_password_policy=0;

修改有效密码长度

set global validate_password_length=4;

设置新密码

set password for root@localhost=password('1234');
flush privileges;

授权远程连接

grant all privileges on *.* to 'root'@'%' identified by '1234' with grant option;
flush privileges;

修改默认编码，解决中文乱码

修改配置文件 /etc/my.cnf 添加如下配置

[mysqld] 
character-set-server=utf8

[client] 
default-character-set=utf8

[mysql] 
default-character-set=utf8

重启服务

systemctl restart mysqld