查询所有会员按最近无交易的排序

Question

User表
UID  UserName
1              A             
2              B
3              C
4              D
5              E
6              F
Order表
OrderId      UID    OrderCode      CreateDate
      1             1           11111           2015-10-01
      2             5           22222           2015-10-02
      3             3           33333           2015-10-05
      4             2           44444           2015-10-18查询的会员表无交易的排在最前面，得到的结果是
UID  UserName
4              D
6              F
1              A
5              E
3              C
2              B求指导！谢谢！

Answer 1

Select uname,user.uid,createtime
From user
Left join order od on od.uid=user.uid

Answer 2

思路： 2个表连接inner join， CreateDate字段为空的可以is null(0)，然后排序CreateDate.

Answer 3

错了是用 left join

Answer 4

Select  t1.UID  t1.UserName
From user as t1
Left join order as t2 
on t2.uid=t2.uid
order by CreateDate