一、系統環境

yum update升級以后的系統版本為

[root@yl-web yl]# cat /etc/redhat-release CentOS Linux release 7.1.1503 (Core) 

二、mysql安裝

一般網上給出的資料都是

#yum install mysql#yum install mysql-server#yum install mysql-devel

安裝mysql和mysql-devel都成功，但是安裝mysql-server失敗，如下： 

[root@yl-web yl]# yum install mysql-serverLoaded plugins: fastestmirrorLoading mirror speeds from cached hostfile * base: mirrors.sina.cn * extras: mirrors.sina.cn * updates: mirrors.sina.cnNo package mysql-server available.Error: Nothing to do

查資料發現是CentOS 7 版本將MySQL數據庫軟件從默認的程序列表中移除，用mariadb代替了。

有兩種解決辦法：

1、方法一：安裝mariadb

MariaDB數據庫管理系統是MySQL的一個分支，主要由開源社區在維護，采用GPL授權許可。開發這個分支的原因之一是：甲骨文公司收購了MySQL后，有將MySQL閉源的潛在風險，因此社區采用分支的方式來避開這個風險。MariaDB的目的是完全兼容MySQL，包括API和命令行，使之能輕松成為MySQL的代替品。

安裝mariadb，大小59 M。

[root@yl-web yl]# yum install mariadb-server mariadb 

mariadb數據庫的相關命令是：

systemctl start mariadb #啟動MariaDBsystemctl stop mariadb #停止MariaDBsystemctl restart mariadb #重啟MariaDBsystemctl enable mariadb #設置開機啟動

所以先啟動數據庫

[root@yl-web yl]# systemctl start mariadb

然后就可以正常使用mysql了 

[root@yl-web yl]# mysql -u root -pEnter password: Welcome to the MariaDB monitor. Commands end with ; or /g.Your MariaDB connection id is 3Server version: 5.5.41-MariaDB MariaDB ServerCopyright (c) 2000, 2014, Oracle, MariaDB Corporation Ab and others.Type 'help;' or '/h' for help. Type '/c' to clear the current input statement.MariaDB [(none)]> show databases;+--------------------+| Database  |+--------------------+| information_schema || mysql  || performance_schema || test  |+--------------------+4 rows in set (0.00 sec)MariaDB [(none)]> 

安裝mariadb后顯示的也是 MariaDB [(none)]> ，可能看起來有點不習慣。下面是第二種方法。

2、方法二：官網下載安裝mysql-server

# wget http://dev.mysql.com/get/mysql-community-release-el7-5.noarch.rpm# rpm -ivh mysql-community-release-el7-5.noarch.rpm# yum install mysql-community-server

安裝成功后重啟mysql服務。

# service mysqld restart

初次安裝mysql，root賬戶沒有密碼。 

[root@yl-web yl]# mysql -u root Welcome to the MySQL monitor. Commands end with ; or /g.Your MySQL connection id is 3Server version: 5.6.26 MySQL Community Server (GPL)Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type 'help;' or '/h' for help. Type '/c' to clear the current input statement.mysql> show databases;+--------------------+| Database  |+--------------------+| information_schema || mysql  || performance_schema || test  |+--------------------+4 rows in set (0.01 sec)mysql>