sql - 划分顺序记录

Question

我在 MS Access 中有一个表，如:

表格

+-----+-----+-----+
| 1st | 2nd | 3rd |
+-----+-----+-----+
| A   |   1 | 100 |
| A   |   2 | 200 |
| A   |   3 | 300 |
| B   |   1 | 100 |
| B   |   2 | 200 |
| B   |   3 | 300 |
| C   |   1 | 100 |
| C   |   2 | 200 |
| C   |   3 | 300 |
+-----+-----+-----+

现在我想从第 3 列读取值，对其进行某种操作并将它们存储到另一个表中，例如:

总结

+-----+---------+---------+
| 1st |   2nd   |   3rd   |
+-----+---------+---------+
| A   | 100/200 | 200/300 |
| B   | 100/200 | 200/300 |
| C   | 100/200 | 200/300 |
+-----+---------+---------+

换句话说，对于 summary.2nd 这意味着:

select table.3rd FROM table where table.1st = A AND table.2nd = 1

除以

select table.3rd FROM table where table.1st = A AND table.2nd = 3

谁能告诉我如何做到这一点？

也许是 VBA/ADO Recordset 等？

Answer 1

一种方法是条件聚合:

select [1st],
       max(iif([2nd] = 1, [3rd], null)) / max(iif([2nd] = 2, [3rd], null)) as [2nd],
       max(iif([2nd] = 2, [3rd], null)) / max(iif([2nd] = 3, [3rd], null)) as [3rd]
from t
group by [1st];