sql入门基础

好用的mysql客户端

https://www.quora.com/What-is-the-best-free-DB-schema-design-tool

https://www.quora.com/What-is-the-best-MySQL-client-for-Mac-OS-X-or-Windows

MySql string 函数

http://dev.mysql.com/doc/refman/5.7/en/string-functions.html