方法一
1、官网下载需要的版本：https://downloads.mysql.com/archives/community/
如果觉得下载慢可以去阿里开源镜像下：https://mirrors.aliyun.com/mysql/MySQL-8.0/?spm=a2c6h.25603864.0.0.65db712bCE0lD5
例如：（方法多多，不一定要这个）我的centos7 下载mysql-8.0.28-1.el7.x86_64.rpm-bundle.tar
2、删除以前安装的残留（如果有mariadb的也要删除）
#查找mysql
rpm -qa | grep mysql
#查找mariadb
rpm -qa |grep mariadb
#没有则不用卸载，有则卸载
rpm -e--nodeps 名称
3、把下载好的mysql传至centos7
（为了方便管理，我把mysql上传至新创建的mysql目录下；如果不会传送至centos7可以去下载finalshell等连接工具，当然如果自己的本机电脑是Linux系统就不需要）
4、查看是否存在libaio
rpm -qa|grep libaio
#如果没有则进行安装
yum install -y libaio
5、解压
tar -xf mysql-8.0.28-1.el7.x86_64.rpm-bundle.tar
6、安装（有顺序要求）
rpm -ivh mysql-community-common-8.0.28-1.el7.x86_64.rpm --nodeps--force
rpm -ivh mysql-community-libs-8.0.28-1.el7.x86_64.rpm --nodeps--force
rpm -ivh mysql-community-devel-8.0.28-1.el7.x86_64.rpm --nodeps--force
rpm -ivh mysql-community-libs-compat-8.0.28-1.el7.x86_64.rpm --nodeps--force
rpm -ivh mysql-community-client-8.0.28-1.el7.x86_64.rpm --nodeps--force
rpm -ivh mysql-community-server-8.0.28-1.el7.x86_64.rpm --nodeps--force
6、启动MySQL服务
systemctl start mysqld
7 、设置MySQL服务开机自启动。
systemctl enable mysqld
8、命令查看/var/log/mysqld.log文件，获取并记录root用户的初始密码。
grep 'temporary password' /var/log/mysqld.log
9、对MySQL进行安全性配置。
mysql_secure_installation
（1）重置密码
Enter password for user root: #输入已获取的root用户初始密码
The existing password for the user account root has expired. Please set a new password.
New password: #输入新的MySQL密码（密码安全性要求比较高，密码需要有大写字母、小写字母、数字、字符组合，；比如:Qkkf56439!）
Re-enter new password: #重复输入新的MySQL密码
The 'validate_password' component is installed on the server.
The subsequent steps will run with the existing configuration
of the component.
Using existing password for root.
Change the password for root ? ((Press y|Y for Yes, any other key for No) :Y #输入Y选择更新MySQL密码。您也可以输入N不再更新MySQL密码。
New password: #输入新的MySQL密码
Re-enter new password: #重复输入新的MySQL密码
Estimated strength of the password: 100
Do you wish to continue with the password provided?(Press y|Y for Yes, any other key for No) :Y #输入Y确认使用已设置的密码。
（2）删除匿名用户。
By default, a MySQL installation has an anonymous user,
allowing anyone to log into MySQL without having to have
a user account created for them. This is intended only for
testing, and to make the installation go a bit smoother.
You should remove them before moving into a production
environment.
Remove anonymous users? (Press y|Y for Yes, any other key for No) :Y #输入Y删除MySQL默认的匿名用户。
Success.
（3）禁止root账号远程登录（出于安全考虑）
Normally, root should only be allowed to connect from
'localhost'. This ensures that someone cannot guess at
the root password from the network.
Disallow root login remotely? (Press y|Y for Yes, any other key for No) :Y #输入Y禁止root远程登录。
Success.
（4）删除test库以及对test库的访问权限。
By default, MySQL comes with a database named 'test' that
anyone can access. This is also intended only for testing,
and should be removed before moving into a production
environment.
Remove test database and access to it? (Press y|Y for Yes, any other key for No) :Y #输入Y删除test库以及对test库的访问权限。
- Dropping test database...
Success.
- Removing privileges on test database...
Success.
（5）重新加载授权表。
Reloading the privilege tables will ensure that all changes
made so far will take effect immediately.
Reload privilege tables now? (Press y|Y for Yes, any other key for No) :Y #输入Y重新加载授权表。
Success.
All done!
10、远程访问MySQL数据库
（1）登录
mysql -uroot -p
（2）创建远程访问账户
mysql> create user 'dmsTest'@'%' identified by '123456'; #创建数据库用户dmsTest,并授予远程连接权限。
mysql> grant all privileges on *.* to 'dmsTest'@'%'; #为dmsTest用户授权数据库所有权限。
mysql> flush privileges; #刷新权限。
方法二（适合小白使用，直接把命令复制粘贴就行）
注：在此解释为什么不适合老手，因为以这种方式安装的MySQL默认最新版本，一般最新版本是不太稳定的，老手更适合安装自己想要的稳定版本
准备：删除以前安装的残留（如果有mariadb的也要删除）
#查找mysql
rpm -qa | grep mysql
#查找mariadb
rpm -qa |grep mariadb
#没有则不用卸载，有则卸载
rpm -e --nodeps 名称
1、更新YUM源
sudo rpm -Uvh https://dev.mysql.com/get/mysql80-community-release-el7-3.noarch.rpm
2、安装MySQL
sudo yum -y install mysql-community-server --enablerepo=mysql80-community --nogpgcheck
3、查看MySQL版本号（一般会直接安装最新版本）
mysql -V
4、启动MySQL服务
systemctl start mysqld
5、设置MySQL服务开机自启动。
systemctl enable mysqld
6、命令查看/var/log/mysqld.log文件，获取并记录root用户的初始密码。
grep 'temporary password' /var/log/mysqld.log
7、对MySQL进行安全性配置。
mysql_secure_installation
（1）重置密码
Enter password for user root: #输入已获取的root用户初始密码
The existing password for the user account root has expired. Please set a new password.
New password: #输入新的MySQL密码（密码安全性要求比较高，密码需要有大写字母、小写字母、数字、字符组合，；比如:Qkkf56439!）
Re-enter new password: #重复输入新的MySQL密码
The 'validate_password' component is installed on the server.
The subsequent steps will run with the existing configuration
of the component.
Using existing password for root.
Change the password for root ? ((Press y|Y for Yes, any other key for No) :Y #输入Y选择更新MySQL密码。您也可以输入N不再更新MySQL密码。
New password: #输入新的MySQL密码
Re-enter new password: #重复输入新的MySQL密码
Estimated strength of the password: 100
Do you wish to continue with the password provided?(Press y|Y for Yes, any other key for No) :Y #输入Y确认使用已设置的密码。
（2）删除匿名用户。
By default, a MySQL installation has an anonymous user,
allowing anyone to log into MySQL without having to have
a user account created for them. This is intended only for
testing, and to make the installation go a bit smoother.
You should remove them before moving into a production
environment.
Remove anonymous users? (Press y|Y for Yes, any other key for No) :Y #输入Y删除MySQL默认的匿名用户。
Success.
（3）禁止root账号远程登录（出于安全考虑）
Normally, root should only be allowed to connect from
'localhost'. This ensures that someone cannot guess at
the root password from the network.
Disallow root login remotely? (Press y|Y for Yes, any other key for No) :Y #输入Y禁止root远程登录。
Success.
（4）删除test库以及对test库的访问权限。
By default, MySQL comes with a database named 'test' that
anyone can access. This is also intended only for testing,
and should be removed before moving into a production
environment.
Remove test database and access to it? (Press y|Y for Yes, any other key for No) :Y #输入Y删除test库以及对test库的访问权限。
- Dropping test database...
Success.
- Removing privileges on test database...
Success.
（5）重新加载授权表。
Reloading the privilege tables will ensure that all changes
made so far will take effect immediately.
Reload privilege tables now? (Press y|Y for Yes, any other key for No) :Y #输入Y重新加载授权表。
Success.
All done!
8、远程访问MySQL数据库
（1）登录
mysql -uroot -p
（2）创建远程访问账户
mysql> create user 'dmsTest'@'%' identified by '123456'; #创建数据库用户dmsTest,并授予远程连接权限。
mysql> grant all privileges on *.* to 'dmsTest'@'%'; #为dmsTest用户授权数据库所有权限。
mysql> flush privileges; #刷新权限。
小知识
如果嫌弃密码安全度要求高，可以自己改
1、查看 MySQL密码策略
SHOW VARIABLES LIKE 'validate_password%';
2、修改密码策略（更改为最低）
set global validate_password.policy=LOW;
3、修改密码的长度（当前为8），如果嫌长可以改为6
set global validate_password.length=6；
