yum安装mysql（指定版）

首先需要删除已经存在的mysql，不然后面会报错：

快速删除：

yum remove  mysql mysql-server mysql-libs mysql-server

查找残余文件：

rpm -qa | grep -i mysql

将查找出来的文件逐条删除。

查找残余目录：

whereis mysql

删除参与目录。

下载YUM源：

#Red Hat7/CentOS7
http://dev.mysql.com/get/mysql57-community-release-el7-9.noarch.rpm

#Red Hat6/CentOS6
http://dev.mysql.com/get/mysql57-community-release-el6-9.noarch.rpm

#Red Hat5/CentOS5
http://dev.mysql.com/get/mysql57-community-release-el5-7.noarch.rpm

其他系统可以查看官网：https://dev.mysql.com/downloads/repo/yum/

或者直接访问下载网址：https://repo.mysql.com/

安装YUM源：

[root@sql-test-HK ~]# rpm -ivh http://dev.mysql.com/get/mysql57-community-release-el7-9.noarch.rpm
Retrieving http://dev.mysql.com/get/mysql57-community-release-el7-9.noarch.rpm
Preparing...                          ################################# [100%]
Updating / installing...
   1:mysql57-community-release-el7-9  ################################# [100%]

查看是否已经安装成功：

[root@sql-test-HK ~]# yum repolist enabled | grep "mysql.*-community.*"
mysql-connectors-community/x86_64 MySQL Connectors Community                 118
mysql-tools-community/x86_64      MySQL Tools Community                       95
mysql57-community/x86_64          MySQL 5.7 Community Server                 364

有最后一行就可以了。

使用这种方式进行安装MySQL会默认安装最新版本，此处就是5.7版本。如过你要安装5.6怎么办？

首先查看被禁用的YUM源：

[root@sql-test-HK ~]# yum repolist all | grep mysql
mysql-connectors-community/x86_64 MySQL Connectors Community     enabled:    118
mysql-connectors-community-source MySQL Connectors Community - S disabled
mysql-tools-community/x86_64      MySQL Tools Community          enabled:     95
mysql-tools-community-source      MySQL Tools Community - Source disabled
mysql-tools-preview/x86_64        MySQL Tools Preview            disabled
mysql-tools-preview-source        MySQL Tools Preview - 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     disabled
mysql56-community-source          MySQL 5.6 Community Server - S disabled
mysql57-community/x86_64          MySQL 5.7 Community Server     enabled:    364
mysql57-community-source          MySQL 5.7 Community Server - S disabled
mysql80-community/x86_64          MySQL 8.0 Community Server     disabled
mysql80-community-source          MySQL 8.0 Community Server - S disabled

我们看到5.6版本是不可用的。

执行如下命令来启动YUM源：

yum install -y yum-utils
yum-config-manager --disable mysql57-community
yum-config-manager --enable mysql56-community

之后就可以看到5.6的源可用了。

[root@sql-test-HK ~]# yum repolist enabled | grep mysql
mysql-connectors-community/x86_64 MySQL Connectors Community                 118
mysql-tools-community/x86_64      MySQL Tools Community                       95
mysql56-community/x86_64          MySQL 5.6 Community Server                 479

安装MySQL：

yum install mysql-community-server

启动MySQL：

[root@sql-test-HK ~]# service mysqld start
Redirecting to /bin/systemctl start mysqld.service
[root@sql-test-HK ~]# service mysqld status
Redirecting to /bin/systemctl status mysqld.service
● mysqld.service - MySQL Server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
   Active: active (running) since Wed 2019-07-31 18:09:12 CST; 41s ago
     Docs: man:mysqld(8)
           http://dev.mysql.com/doc/refman/en/using-systemd.html
  Process: 12960 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid $MYSQLD_OPTS (code=exited, status=0/SUCCESS)
  Process: 12886 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=0/SUCCESS)
 Main PID: 12964 (mysqld)
   CGroup: /system.slice/mysqld.service
           └─12964 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid

Jul 31 18:09:08 sql-test-HK systemd[1]: Starting MySQL Server...
Jul 31 18:09:12 sql-test-HK systemd[1]: Started MySQL Server.

可以同过如下明明查看MySQL的初始密码：

[root@sql-test-HK ~]# grep 'temporary password' /var/log/mysqld.log
2019-07-31T10:09:09.630812Z 1 [Note] A temporary password is generated for root@localhost: Ogue1n7P1?&L

设置密码（在5.6里面貌似没有初始密码，可以直接设置）：

mysql_secure_installation

当然我们可以通过初始密码直接在数据库中使用grant来进行设置。

之后就可以进行登陆了：

mysql -uroot -p

需要说明的是，在安装的时候如果出现如下错误：

Error: Package: mysql-community-server-5.7.27-1.el7.x86_64 (mysql57-community)
           Requires: mysql-community-common(x86-64) = 5.7.27-1.el7
           Installed: mysql-community-common-8.0.17-1.el7.x86_64 (@mysql80-community)
               mysql-community-common(x86-64) = 8.0.17-1.el7
           Available: mysql-community-common-5.7.9-1.el7.x86_64 (mysql57-community)
               mysql-community-common(x86-64) = 5.7.9-1.el7
　　　　　　　　　　　　　　　　......
           Available: mysql-community-common-5.7.27-1.el7.x86_64 (mysql57-community)
               mysql-community-common(x86-64) = 5.7.27-1.el7
 You could try using --skip-broken to work around the problem
 You could try running: rpm -Va --nofiles --nodigest

那证明你没有严格执行第一步，重新指定前面的操作再次安装就可以了。