一、安装

　　参考：https://dev.mysql.com/doc/refman/5.7/en/linux-installation-yum-repo.html

# 检测系统中是否安装了mysql
yum list installed | grep mysql

### 显示内容 ###
### 我已经装过了……没装之前可能什么都没有，也可能有低版本的mysql
mysql-community-client.x86_64
                     5.7.23-1.el6       @mysql57-community-dmr                  
mysql-community-common.x86_64
                     5.7.23-1.el6       @mysql57-community-dmr                  
mysql-community-libs.x86_64
                     5.7.23-1.el6       @mysql57-community-dmr                  
mysql-community-release.noarch
                     el6-5              @/mysql-community-release-el6-5.noarch  
mysql-community-server.x86_64
                     5.7.23-1.el6       @mysql57-community-dmr       



# 卸载低版本mysql，才能安装上mysql5.7
# remove后面是上面显示的文件（-y表示全过程选是）,上面出现的全部都要remove掉
yum -y remove mysql-community-client.x86_64 mysql-community-common.x86_64 ...

### 显示内容 ###
...
Removed:
  mysql-community-client.x86_64    0:5.7.23-1.el6   mysql-community-common.x86_64 0:5.7.23-1.el6    
  mysql-community-libs.x86_64 0:5.7.23-1.el6   mysql-community-release.noarch 0:el6-5         

Dependency Removed:
  mysql-community-server.x86_64 0:5.7.23-1.el6

Complete!



# 再检测一次，直到为空

# 下载mysql的yum源（el6-5表示惹的redhat6和sentos6-mysql5）
wget http://repo.mysql.com/mysql-community-release-el6-5.noarch.rpm

# 载入yum源
yum install mysql-community-release-el6-5.noarch.rpm

# 查看mysql可用的安装源（安装源里面有mysql5的好几个版本）
yum repolist enabled | grep mysql

### 显示内容 ###
mysql-connectors-community MySQL Connectors Community                         59
mysql-tools-community      MySQL Tools Community                              65
mysql56-community          MySQL 5.6 Community Server                        453



# 发现没有5.7版本的，修改repo文件，把5.7版本改为可用，5.6版本改为不可用
vi /etc/yum.repos.d/mysql-community.repo

### 显示内容 ###
############################################################################################################

[mysql-connectors-community]
name=MySQL Connectors Community
baseurl=http://repo.mysql.com/yum/mysql-connectors-community/el/6/$basearch/
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/6/$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/6/$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/6/$basearch/
enabled=1 #把这个1改成0
gpgcheck=1
gpgkey=file:/etc/pki/rpm-gpg/RPM-GPG-KEY-mysql

# Note: MySQL 5.7 is currently in development. For use at your own risk.
# Please read with sub pages: https://dev.mysql.com/doc/relnotes/mysql/5.7/en/
[mysql57-community-dmr]
name=MySQL 5.7 Community Server Development Milestone Release
baseurl=http://repo.mysql.com/yum/mysql-5.7-community/el/6/$basearch/
enabled=0 #把这个0改成1
gpgcheck=1
gpgkey=file:/etc/pki/rpm-gpg/RPM-GPG-KEY-mysql

############################################################################################################



# 按i进入编辑模式！
# 输入数字不要使用小键盘！
# 按ESC键退出编辑模式！
# 输入:wq 回车--保存并退出！

# 再次检查