CentOS7的yum源中默認好像是沒有mysql的。為了解決這個問題，我們要先下載mysql的repo源。

1. 下載mysql的repo源

$ wget http://repo.mysql.com/mysql-community-release-el7-5.noarch.rpm

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

$ sudo rpm -ivh mysql-community-release-el7-5.noarch.rpm

安裝這個包後，會獲得兩個mysql的yum repo源：/etc/yum.repos.d/mysql-community.repo，/etc/yum.repos.d/mysql-community-source.repo。

3. 安裝mysql

$ sudo yum install mysql-server

根據步驟安裝就可以了，不過安裝完成後，沒有密碼，需要重置密碼。

4. 重置密碼

重置密碼前，首先要登錄

$ mysql -u root

登錄時有可能報這樣的錯：ERROR 2002 (HY000): Can‘t connect to local MySQL server through socket ‘/var/lib/mysql/mysql.sock‘ (2)，原因是/var/lib/mysql的訪問權限問題。下面的命令把/var/lib/mysql的擁有者改為當前用戶：

$ sudo chown -R openscanner:openscanner /var/lib/mysql

然後，重啟服務：

$ service mysqld restart

接下來登錄重置密碼：

$ mysql -u root

mysql > use mysql;mysql > update user set password=password(‘123456‘) where user=‘root‘;mysql > exit;

5. 需要更改權限才能實現遠程連接MYSQL數據庫

可以通過以下方式來確認：

root#mysql -h localhost -uroot -p

Enter password: ******

Welcome to the MySQL monitor.   Commands end with ; or \g.

Your MySQL connection id is 4 to server version: 4.0.20a-debug

Type ‘help;’ or ‘\h’ for help. Type ‘\c’ to clear the buffer.

mysql> use mysql; (此DB存放MySQL的各種配置信息)

Database changed

mysql> select host,user from user; (查看用戶的權限情況)

mysql> select host, user, password from user;
+-----------+------+-------------------------------------------+
| host       | user | password                                   |
+-----------+------+-------------------------------------------+
| localhost | root | *4ACFE3202A5FF5CF467898FC58AAB1D615029441 |
| 127.0.0.1 | root | *4ACFE3202A5FF5CF467898FC58AAB1D615029441 |
| localhost |       |                                            |
+-----------+------+-------------------------------------------+
4 rows in set (0.01 sec)

由此可以看出，只能以localhost的主機方式訪問。
解決方法：
mysql> Grant all privileges on *.* to ‘root‘@‘%‘ identified by ‘123456‘ with grant option;
(%表示是所有的外部機器，如果指定某一臺機，就將%改為相應的機器名；‘root’則是指要使用的用戶名，)
mysql> flush privileges;    (運行此句才生效，或者重啟MySQL)
Query OK, 0 rows affected (0.03 sec)

再次查看。。

mysql> select host, user, password from user;
+-----------+------+-------------------------------------------+
| host       | user | password                                   |
+-----------+------+-------------------------------------------+
| localhost | root | *4ACFE3202A5FF5CF467898FC58AAB1D615029441 |
| 127.0.0.1 | root | *4ACFE3202A5FF5CF467898FC58AAB1D615029441 |
| localhost |       |                                            |
| %          | root | *4ACFE3202A5FF5CF467898FC58AAB1D615029441 |
+-----------+------+-------------------------------------------+
4 rows in set (0.01 sec)

centos7下使用yum安裝mysql