摘要： img class="desc_img" src="http://image.baidu.com/search/detail?ct=503316480&z=&tn=baiduimagedetail&ipn=d&word=%E7%BE%8E%E6%99%AF%E5%9B%BE%E7%89%87&step_word=&ie=utf-8&in=&cl=2&lm=-1&st=-1&cs=4045164136,3453875281&os=2350101120,4146613540&simid=3481191515,286189991&pn=66&rn=1&di=142937176250&ln=1000&fr=&fmq=1471433657767_R&ic=0&s=undefined&se=&sme=&tab=0&width=&height=&face=undefined&is=&istype=2&ist=&jit=&bdtype=0&adpicid=0&pi=&gsm=1e&objurl=http:%2F%2Fwww.taopic.com%2Fuploads%2Fallimg%2F120619 阅读全文

摘要： 我学习的是MySQL，学习写sql语句过程中遇到Group By 和 Union。 大家乐意看这两个链接，写的很好 Group By： www.cnblogs.com/rainman/archive/2013/05/01/3053703.html Union : http://www.jb51.ne 阅读全文