环境说明

centos7
注意：这是我安装很多次失败中总结，希望你可以按照我的步骤，一步一步来，应该是不会有问题的。
如果你已经安装了mysql，需要先卸载，卸载请参考：
Centos7 完全卸载mysql

检查 MariaDB 是否安装

yum list installed | grep mariadb

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卸载全部 MariaDB 相关

yum -y remove mariadb*

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数据准备

下载mysql安装包

[root@localhost ~]# cd /usr/local/src/
[root@localhost src]# wget https://dev.mysql.com/get/mysql80-community-release-el7-3.noarch.rpm

下载完后可以目录中看到：

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安装mysql源

rpm -ivh mysql80-community-release-el7-3.noarch.rpm

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检查 MySQL 的 YUM 源是否安装成功

yum repolist enabled | grep "mysql.*-community.*"

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查看 MySQL 版本

yum repolist all | grep mysql

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安装 MySQL

yum install mysql-community-server

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启动mysql服务

systemctl start mysqld
附加命令
查看MySQL状态 systemctl status mysqld
关闭MySQL服务 systemctl stop mysqld
重启MySQL服务 systemctl restart mysqld

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查看自动生成的临时密码

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

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这个密码先自己保存下

登录mysql

使用刚才生成的临时密码

mysql -uroot -p

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这时候对数据的操作会报错，必须先改密码

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mysql8.0修改密码和以往不同，我看过别的教程，修改成功后，无法使用该密码进行登录，正确方式如下(引号后面是密码)

密码需要包含大小写字母、数字、符号长度也不能过短，暂时先弄一个很长的，一会再改。
ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY "#20as3SElk3@wwerwer232342432342343223243sdfasfafasdsds0ew98";

ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY "#20as3SElk3@wwerwer232342432342343223243sdfasfafasdsds0ew98";

刷新

FLUSH privileges;

此时我们退出，重新登录看看效果
（输入密码我们用复制的，在xshell中操作）

mysql> quit;
Bye
[root@localhost src]# mysql -uroot -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 9
Server version: 8.0.17 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> 

可以登录！

设置安全策略

因为要把刚才的密码改的简单一点，这里需要先修改安全策略，mysql8.0修改安全策略的命令和5.7不同，具体如下

先选择数据库：
use mysql;

5.7语法：
set global validate_password_policy=0;set global validate_password_length=1;

8.0语法：
set global validate_password.policy=0;
set global validate_password.length=1;

最后都要刷新：
FLUSH privileges;

修改密码

mysql> use mysql;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY "123456";
Query OK, 0 rows affected (0.00 sec)

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

退出重新登录

输入刚才修改的密码

mysql> quit;
Bye
[root@localhost src]# mysql -uroot -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 11
Server version: 8.0.17 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> 

设置远程访问

mysql> CREATE USER 'root'@'%' IDENTIFIED BY '123456';
Query OK, 0 rows affected (2.30 sec)

mysql> GRANT ALL ON *.* TO 'root'@'%';
Query OK, 0 rows affected (0.01 sec)

mysql> ALTER USER 'root'@'%' IDENTIFIED WITH mysql_native_password BY '123456';
Query OK, 0 rows affected (0.00 sec)

mysql> FLUSH PRIVILEGES; 
Query OK, 0 rows affected (0.03 sec)

mysql> 

开启防火墙

[root@localhost src]# firewall-cmd --zone=public --add-port=3306/tcp --permanent
success
[root@localhost src]# firewall-cmd --reload
success

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