如何连接两个没有重复的表？

Question

我有一个看起来像这样的表:

id_in  | date_in   
-------|--------------------------
1      | 2016-04-29 02:00:00

还有一个看起来像这样的表:

id_out    |  date_out
----------|--------------------------
1         | 2016-04-29 03:00:00
2         | 2016-04-29 04:00:00
3         | 2016-04-29 05:00:00

我想编写一个输出如下所示的查询:

id_in | date_in                     | id_out                     | date_out
------|---------------------------- |----------------------------|---------------------------
1     | 2016-04-29 02:00:00         | 1                          |2016-04-29 03:00:00
NULL  |  NULL                       | 2                          |2016-04-29 04:00:00
NULL  |  NULL                       | 3                          |2016-04-29 05:00:00

Answer 1

你可以这样做left join:

select i.id_in, i.date_in, o.id_out, o.date_out
from outtable o left join
     intable i
     on o.id_in = i.id_out;