sql相同value，求最大的id

先上图：

  select t1.id,t1.coordinatename  from t_coordinate t1 join  t_coordinate t2  on  t1.parentid = t2.parentid where t1.id != t2.id  and t1.coordinatename = t2.coordinatename 

题目大概就是：找出coordinatename相同的最大的ID？

select max(t1.id),t1.coordinatename  from t_coordinate t1 join  t_coordinate t2  on  t1.parentid = t2.parentid where t1.id != t2.id  and t1.coordinatename = t2.coordinatename  group by t1.coordinatename

换汤不换药：或者找出id相同时最大的value？

参考百度知道：http://zhidao.baidu.com/question/93647210.html

参考bbs：http://bbs.csdn.net/topics/290076464