CentOS7的yum源中默认好像是没有mysql的。为了解决这个问题，我们要先下载mysql的repo源。

1. 下载mysql的repo源

2. 安装mysql-community-release-el7-5.noarch.rpm包

安装这个包后，会获得两个mysql的yum repo源：/etc/yum.repos.d/mysql-community.repo，/etc/yum.repos.d/mysql-community-source.repo。

3. 安装mysql

根据步骤安装就可以了，不过安装完成后，没有密码，需要重置密码。

4. 重置密码

修改MySQL的登录设置： 
# vim /etc/my.cnf
在[mysqld]的段中加上一句：skip-grant-tables
例如：
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
skip-grant-tables
保存并且退出vi。

重新启动mysqld 
# service mysqld restart
Stopping MySQL: [ OK ]
Starting MySQL: [ OK ]

登录并修改MySQL的root密码 
# mysql
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 3 to server version: 3.23.56
Type ‘help;’ or ‘\h’ for help. Type ‘\c’ to clear the buffer.
mysql> USE mysql ;
Database changed
mysql> UPDATE user SET Password = password ( ‘new-password’ ) WHERE User = ‘root’ ;
Query OK, 0 rows affected (0.00 sec)
Rows matched: 2 Changed: 0 Warnings: 0
mysql> flush privileges ;
Query OK, 0 rows affected (0.01 sec)
mysql> quit

将MySQL的登录设置修改回来 
# vim /etc/my.cnf
将刚才在[mysqld]的段中加上的skip-grant-tables删除
保存并且退出vim

重新启动mysqld 
# service mysqld restart
Stopping MySQL: [ OK ]
Starting MySQL: [ OK ]

方式二：

# step1：卸载

[root@codecycle ~]# rpm -qa | grep mysql

mysql-5.1.73-3.el6_5.x86_64

mysql-libs-5.1.73-3.el6_5.x86_64

mysql-server-5.1.73-3.el6_5.x86_64

[root@codecycle ~]# rpm -e --nodeps mysql-5.1.73-3.el6_5.x86_64 mysql-libs-5.1.73-3.el6_5.x86_64 mysql-server-5.1.73-3.el6_5.x86_64

# step2: 下载yum包，导入本地

[root@codecycle ~]# yum localinstall /usr/local/src/mysql-community-release-el6-5.noarch.rpm

# step3：安装

[root@codecycle ~]# yum install mysql-community-server

# step4：启动

[root@codecycle ~]# service mysqld start

# step5：开机启动

[root@codecycle ~]# chkconfig --list | grep mysqld

mysqld 0:off 1:off 2:off 3:off 4:off 5:off 6:off

[root@codecycle ~]# chkconfig mysqld on

# step6：设置本地登录密码

[root@codecycle ~]# mysqladmin -uroot -p password 123456

# step7：设置远程登录密码

[root@codecycle ~]# mysql -uroot -p123456

mysql> grant all privileges on *.* to root@'%' identified by 'qaz123wsx' with grant option;

mysql> flush privileges;