在centos 6 下安装mysql 5.6

    因为工作需要，要在redhat环境下用mysql，没想到与win下使用mysql有些区别，踩了几个坑，于是有这篇入门安装手册。

==========分割线========

1. 下载
   

   用的是2进制包，源码包还要折腾，就不弄了，32位的地址 http://cdn.mysql.com/Downloads/MySQL-5.6/mysql-5.6.12-linux-glibc2.5-i686.tar.gz 包有点儿大，285M   
   

2. 安装
   参考解压后目录下的文件INSTALL-BINARY，里面有一段脚本，按着上面一步步执行下来就好
   

   shell> groupadd mysql
   shell> useradd -r -g mysql mysql
   shell> cd /usr/local
   shell> tar zxvf /path/to/mysql-VERSION-OS.tar.gz
   shell> ln -s full-path-to-mysql-VERSION-OS mysql
   shell> cd mysql
   shell> chown -R mysql .
   shell> chgrp -R mysql .
   shell> scripts/mysql_install_db --user=mysql
   shell> chown -R root .
   shell> chown -R mysql data
   # Next command is optional
   shell> cp support-files/my-medium.cnf /etc/my.cnf
   shell> bin/mysqld_safe --user=mysql &
   # Next command is optional
   shell> cp support-files/mysql.server /etc/init.d/mysql.server

3. 踩坑之一：修改root密码
   默认登录是不要密码的，直接用bin/mysql就进去了，安全系数太低
   

   mysql> select host, user, password from mysql.user;

   显示当前所有用户信息，可以看见密码全为空，还有匿名帐号
   删除匿名

   mysql> DELETE FROM mysql.user WHERE User = '';

   替换root密码
   

   SET PASSWORD FOR root@"相关host" = PASSWORD('你的密码');
   FLUSH PRIVILEGES;

   
   
4. 踩坑之二：允许远程链接
   首先，要确保防火墙没有阻拦3306端口，切记！为了这个我排查了2个钟头……
   然后，加入允许远程登录的用户信息
   

   GRANT USAGE ON *.* TO '用户名'@'%' IDENTIFIED BY '密码' WITH GRANT OPTION;
   FLUSH PRIVILEGES;

   
   
5. 踩坑之三：字符集
   mysql默认的字符集是坑爹的拉丁文，最好换成utf8
   编辑 /etc/my.cnf
   

   [mysqld]
   # 添加字符集指定
   character-set-server=utf8

   然后重启mysql服务，进去看看字符集对了没
   

   mysql> \s
   --------------
   /usr/local/mysql/bin/mysql  Ver 14.14 Distrib 5.6.12, for linux-glibc2.5 (i686) using  EditLine wrapper
   
   Connection id:		2
   Current database:	
   Current user:		root@localhost
   SSL:			Not in use
   Current pager:		stdout
   Using outfile:		''
   Using delimiter:	;
   Server version:		5.6.12 MySQL Community Server (GPL)
   Protocol version:	10
   Connection:		Localhost via UNIX socket
   Server characterset:	utf8
   Db     characterset:	utf8
   Client characterset:	utf8
   Conn.  characterset:	utf8
   UNIX socket:		/tmp/mysql.sock
   Uptime:			27 sec