环境
[root@node1 ~]# cat /etc/redhat-release
CentOS Linux release 7.1.1503 (Core)
[root@node1 ~]# uname -a
Linux node4 3.10.0-229.el7.x86_64 #1 SMP Fri Mar 6 11:36:42 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
检查系统是否自带安装mysql
[root@node1 ~]# yum list installed | grep mysql
[root@node1 ~]#
如果有将其删除
[root@node1 ~]# yum -y remove mysql-libs.x86_64
Loaded plugins: fastestmirror
No Match for argument: mysql-libs.x86_64
No Packages marked for removal
由于mysql的yum源服务器在国外，所以下载速度会比较慢，还好mysql5.6只有79M大，而mysql5.7就有182M了，所以这里想安装mysql5.6
下载rpm包
[root@node1 ~]# wget http://repo.mysql.com/mysql-community-release-el7-7.noarch.rpm
解压
[root@node1 ~]# rpm -ivh mysql-community-release-el7-7.noarch.rpm
检查mysql源是否安装成功
[root@node2 ~]# yum repolist enabled | grep "mysql.*-community.*"
mysql-connectors-community/x86_64 MySQL Connectors Community 42
mysql-tools-community/x86_64 MySQL Tools Community 51
mysql56-community/x86_64 MySQL 5.6 Community Server
查看是否已经有mysql可安装文件
root@node1 ~]# yum repolist all | grep mysql
mysql-connectors-community/x86_64 MySQL Connectors Community enabled: 42
mysql-connectors-community-source MySQL Connectors Community - S disabled
mysql-tools-community/x86_64 MySQL Tools Community enabled: 51
mysql-tools-community-source MySQL Tools Community - Source disabled
mysql55-community/x86_64 MySQL 5.5 Community Server disabled
mysql55-community-source MySQL 5.5 Community Server - S disabled
mysql56-community/x86_64 MySQL 5.6 Community Server enabled: 344
mysql56-community-source MySQL 5.6 Community Server - S disabled
mysql57-community/x86_64 MySQL 5.7 Community Server disabled
mysql57-community-source MySQL 5.7 Community Server - S disabled
可以修改 mysql-community.repo 源，更改默认安装的mysql版本比如要安装5.6版本，将5.7源的enabled=1改成enabled=0。然后再将5.6源的enabled=0改成enabled=1即可。改完之后的效果如下所示：
[root@node2 ~]# vim /etc/yum.repos.d/mysql-community.repo
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql
[mysql-tools-community]
name=MySQL Tools Community
baseurl=http://repo.mysql.com/yum/mysql-tools-community/el/7/$basearch/
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql
# Enable to use MySQL 5.5
[mysql55-community]
name=MySQL 5.5 Community Server
baseurl=http://repo.mysql.com/yum/mysql-5.5-community/el/7/$basearch/
enabled=0
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql
# 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/$basearch/
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql
[mysql57-community]
name=MySQL 5.7 Community Server
baseurl=http://repo.mysql.com/yum/mysql-5.7-community/el/7/$basearch/
enabled=0
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql
安装mysql 服务器（网速决定安装速度）
[root@node1 ~]# yum -y install mysql-community-server
启动 mysql 服务
[root@node1 ~]# systemctl start mysql
查看mysql 的启动状态
[root@node1 ~]# systemctl status mysqld
mysqld.service - MySQL Community Server
Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled)
Active: active (running) since Wed 2017-08-23 11:28:23 EDT; 38min ago
Process: 2904 ExecStartPost=/usr/bin/mysql-systemd-start post (code=exited, status=0/SUCCESS)
Process: 2843 ExecStartPre=/usr/bin/mysql-systemd-start pre (code=exited, status=0/SUCCESS)
Main PID: 2903 (mysqld_safe)
开机启动
[root@node1 ~]# systemctl enable mysqld
[root@node1 ~]# systemctl daemon-reload