Question

我有2个表，要在MS Access中进行FULL OUTER JOIN。

说我有表A ，它看起来像这样：

A.ID    |  A.Value  | A.DATE
--------+-----------+----------
  1     |     30    | 05/2018
  1     |     28    | 06/2018
  1     |     26    | 07/2018
  2     |     250   | 04/2018
  2     |     252   | 05/2018
  2     |     240   | 06/2018

和表B 如下：

B.ID    |  B.FCST   | B.OUTDATE
--------+-----------+-----------
  1     |     35    | 06/2018
  1     |     33    | 07/2018
  1     |     30    | 08/2018
  2     |     300   | 06/2018
  2     |     280   | 07/2018
  2     |     260   | 08/2018

我需要执行Joins and Unions来实现此目的：

 A.ID   |  A.Value  | A.DATE  |  B.FCST   | B.OUTDATE
--------+-----------+---------+-----------+------------
  1     |     30    | 05/2018 |     -     |     -
  1     |     28    | 06/2018 |     35    |   06/2018
  1     |     26    | 07/2018 |     33    |   07/2018
  1     |     -     |    -    |     30    |   08/2018
  2     |     250   | 04/2018 |     -     |     -
  2     |     252   | 05/2018 |     -     |     -
  2     |     240   | 06/2018 |     300   |   06/2018
  2     |     -     |    -    |     280   |   07/2018
  2     |     -     |    -    |     260   |   08/2018

因此，我需要使用A.ID = B.ID和A.DATE = B.OUTDATE进行内部联接，然后以某种方式从Table.A获取“较早”数据到内部的“坐在顶部”连接数据，而来自Table.B的“后”数据则相反。到目前为止，这是我的尝试：

Select A.ID, A.Value, A.DATE, B.FCST, B.OUTDATE
FROM Table.A JOIN Table.B ON A.ID = B.ID AND A.DATE = B.OUTDATE

UNION ALL

Select A.ID, A.Value, A.DATE, B.FCST, B.OUTDATE
FROM Table.A LEFT JOIN Table.B ON A.ID = B.ID;
WHERE B.ID IS NULL

UNION ALL

Select A.ID, A.Value, A.DATE, B.FCST, B.OUTDATE
FROM Table.A RIGHT JOIN Table.B ON A.ID = B.ID
WHERE A.ID IS NULL

ORDER BY A.ID ASC;

但是我错过了它出现的痕迹。我收到重复的行，看起来就像是内部联接。我会很乐意听取任何建议以帮助实现这一目标。

Answer 1

我建议两个left joins的并集给出与完全外部相同的结果，最后带有一点点排序以产生所需的排序：

select c.* from
(
    select a.id, a.value, a.date, b.fcst, b.outdate
    from a left join b on a.id = b.id and a.date = b.outdate
    union
    select b.id, a.value, a.date, b.fcst, b.outdate
    from b left join a on a.id = b.id and a.date = b.outdate
) c
order by c.id, nz(c.date, c.outdate)

MS Access Full Outer Join是否使用2个字段？

1 个答案: