安装前说明：
1、以下安装教程部分内容直接粘引用的是之前在我CSDN中的图片解释内容，对于正常安装没有影响。
2、以下安装教程在本次书写中已经过实践（真实服务器），加上之前在CSDN中的至少实践两次以上。
官网下载MySQL
官网：https://dev.mysql.com/downloads/repo/yum/
下载自己需要的版本后，如下
[root@VM-0-8-centos software]# ls mysql80-community-release-el7-3.noarch.rpm [root@VM-0-8-centos software]#
首先本地安装 rpm yum localinstall mysql80-community-release-el7-3.noarch.rpm
[root@VM-0-8-centos software]# yum localinstall mysql80-community-release-el7-3.noarch.rpm Loaded plugins: fastestmirror, langpacks Examining mysql80-community-release-el7-3.noarch.rpm: mysql80-community-release-el7-3.noarch Marking mysql80-community-release-el7-3.noarch.rpm to be installed Resolving Dependencies --> Running transaction check ---> Package mysql80-community-release.noarch 0:el7-3 will be installed --> Finished Dependency Resolution Dependencies Resolved =========================================================================================================================== Package Arch Version Repository Size =========================================================================================================================== Installing: mysql80-community-release noarch el7-3 /mysql80-community-release-el7-3.noarch 31 k Transaction Summary =========================================================================================================================== Install 1 Package Total size: 31 k Installed size: 31 k Is this ok [y/d/N]: y Downloading packages: Running transaction check Running transaction test Transaction test succeeded Running transaction Installing : mysql80-community-release-el7-3.noarch 1/1 Verifying : mysql80-community-release-el7-3.noarch 1/1 Installed: mysql80-community-release.noarch 0:el7-3 Complete! [root@VM-0-8-centos software]#
上述安装完后会在本地建立一个mysql仓库，接着我们指定仓库中的mysql版本（即将要安装的）
指定安装版本—–编辑mysql-community.repo文件 vi /etc/yum.repos.d/mysql-community.repo
具体代码如下：
# Enable to use MySQL 5.6 [mysql56-community] name=MySQL 5.6 Community Server baseurl=http://repo.mysql.com/yum/mysql-5.6-community/el/7/$basearch/ enabled=0 gpgcheck=1 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql # Enable to use MySQL 5.7 [mysql57-community] name=MySQL 5.7 Community Server baseurl=http://repo.mysql.com/yum/mysql-5.7-community/el/7/$basearch/ enabled=1 gpgcheck=1 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql [mysql80-community] name=MySQL 8.0 Community Server baseurl=http://repo.mysql.com/yum/mysql-8.0-community/el/7/$basearch/ enabled=0 gpgcheck=1 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql
其中，enabled=0表示不安装，我们找到mysql5.7然后将enabled设置为1，其余设置为0（以防默认）。
设置好安装版本后，然后安装 yum install mysql-community-server
安装完成后，登录mysql，因在安装过程中，没有设置密码，第一次登录用我们直接回车看提示进行试探。
第一次登录出现如下情况 ：
[root@master yum.repos.d]# mysql -u root -p Enter password: ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)
解决办法第一步，查看mysql服务状态
systemctl status mysqld
[root@master]# systemctl status mysqld
● mysqld.service - MySQL Server
Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
Active: inactive (dead)
Docs: man:mysqld(8)
http://dev.mysql.com/doc/refman/en/using-systemd.html
[root@master]#
可以看出服务没有激活
解决办法第二步，开启mysql服务
[root@master]# systemctl start mysqld
[root@master]# systemctl status mysqld
● mysqld.service - MySQL Server
Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
Active: active (running) since Wed 2019-09-25 22:06:12 CST; 2s ago
Docs: man:mysqld(8)
http://dev.mysql.com/doc/refman/en/using-systemd.html
Process: 1995 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid $MYSQLD_OPTS (code=exited, status=0/SUCCESS)
Process: 1922 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=0/SUCCESS)
Main PID: 1998 (mysqld)
CGroup: /system.slice/mysqld.service
└─1998 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid...
Sep 25 22:06:05 master systemd[1]: Starting MySQL Server...
Sep 25 22:06:12 master systemd[1]: Started MySQL Server.
[root@master]#
服务已经开启，我们再次无密码登录
[root@master yum.repos.d]# mysql -u root -p Enter password: ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)
发现没有密码被拒绝，此时应该想到好看日志，首先查看mysql的错误日志在那个文件
查看mysql错误日志在那个文件夹下
[root@master yum.repos.d]# cat /etc/my.cnf # For advice on how to change settings please see # http://dev.mysql.com/doc/refman/5.7/en/server-configuration-defaults.html [mysqld] # # Remove leading # and set to the amount of RAM for the most important data # cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%. # innodb_buffer_pool_size = 128M # # Remove leading # to turn on a very important data integrity option: logging # changes to the binary log between backups. # log_bin # # Remove leading # to set options mainly useful for reporting servers. # The server defaults are faster for transactions and fast SELECTs. # Adjust sizes as needed, experiment to find the optimal values. # join_buffer_size = 128M # sort_buffer_size = 2M # read_rnd_buffer_size = 2M datadir=/var/lib/mysql socket=/var/lib/mysql/mysql.sock # Disabling symbolic-links is recommended to prevent assorted security risks symbolic-links=0 log-error=/var/log/mysqld.log pid-file=/var/run/mysqld/mysqld.pid [root@master yum.repos.d]# cat /var/log/mysqld.log
从上面看有注意到mysql的错误日志位置（log-error=/var/log/mysqld.log）
查看mysql.log
复制密码再次登录
[root@master yum.repos.d]# mysql -u root -p Enter password: Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 3 Server version: 5.7.27 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>
登录成功！查看数据库试试
mysql> show databases; ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement. mysql>
提示要重置密码
修改密码第一步：设置密码安全检验（降低）
mysql> set global validate_password_policy=0; Query OK, 0 rows affected (0.00 sec) mysql> set global validate_password_length=1; Query OK, 0 rows affected (0.00 sec)
重新登录
[root@master yum.repos.d]# mysql -u root -p Enter password: Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 4 Server version: 5.7.27 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.
查看策略表
可以看出，密码长度最小设置文4位，设置密码要求已经最低。到了这个阶段，mysql5.7已经安装好了。
为了方便远程连接，现给root用户授权。
update user set host='%' where user='root';
至此，MySQL5.7在Linux系统上的安装已完成，如配置过程中有遇到其他问题，欢迎留言讨论！
请先 ！