来自两个表的 MS Access JOIN 列 - NOT UNION

Question

我需要在 MS Access 中编写一个查询，以按 2 个日期列获取操作计数。 我的表的结构是

开始日期	结束日期	f1	f2	f3
2022-12-01	2022-12-05	f1	f2	f3
2022-11-15	2022-12-07	f1	f2	f3
2022-12-06	2022-12-07	f1	f2	f3
2022-11-15	2022-12-06	f1	f2	f3

对于一个月的所有日期，我需要 output

日期	日期总 start_date	总 end_date 日期
2022-11-15	1个	0
2022-12-01	1个	0
2022-12-05	0	1个
2022-12-06	1个	1个
2022-12-07	0	2个

我所做的是（这是不正确的，因为在给定的 start_date 上有可能，计数为零，对于某些 end_date 计数为零）

SELECT start_date, count(start_date) as startcount, tbl2.endcount FROM tbl
FULL OUTER JOIN (SELECT end_date, count(end_date) as endcount FROM tbl GROUP BY end_date) as tbl2
ON start_date=tbl2.end_date
GROUP BY start_date
ORDER BY start_date

有什么建议么？

我已经检查了现有的答案，但它们不符合要求，因为在其他答案中他们正在做结果的 UNION，这不是我的问题。

Answer 1

我没有意识到只需要一票就可以重新打开并回答...
我在评论中写得最多，但第一种方法如下所示：

SELECT TheDate, SUM(startcount) AS TotalStart, SUM(endcount) AS TotalEnd
FROM (
    SELECT start_date as TheDate, count(*) as startcount, 0 AS endcount 
    FROM tbl
    GROUP BY start_date
    
    UNION ALL
    
    SELECT end_date as TheDate, 0 as startcount, count(*) as endcount 
    FROM tbl 
    GROUP BY end_date
)
GROUP BY TheDate

而 JJ32 是正确的，这可以简化为：

SELECT TheDate, SUM(startcount) AS TotalStart, SUM(endcount) AS TotalEnd
FROM (
    SELECT start_date as TheDate, 1 as startcount, 0 AS endcount 
    FROM tbl
    
    UNION ALL
    
    SELECT end_date as TheDate, 0 as startcount, 1 as endcount 
    FROM tbl 
)
GROUP BY TheDate

这基本上是一个 UNPIVOT 操作。