关于sql server：如何在SQL中按日期范围连接多个表？

How to join multiple tables by date range in SQL?

我对SQL比较陌生。我一直在努力编写一个非常简单的查询，它返回一行。

我试图从几个不同的表中选择多个列值计数，每个计数都在相同的日期范围内。

我的数据库中的表如下所示：

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| CreationDate | LastName | EventType |
|:--------------------|------------:|:------------:| ...
| 2013-01-02 18:00:21 | Doe | 2 |
| 2013-01-07 18:00:24 | Blanks | 2 | ...
| 2013-01-09 17:00:21 | Puccini | 1 |

所有表都有类似的creationdate列。

我现在的查询是一个像下面这样的单一联接(似乎可以工作)。我正在尝试添加一个或多个联接，以便可以将每个表的多个计数返回到单行结果中。我当前的查询：

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DECLARE @startdate DATETIME = '##startdate##';
DECLARE @enddate DATETIME = '##enddate##';

SELECT ISNULL(t2.Year, t1.Year) ,
ISNULL(t2.Month, t1.Month) ,
t1.LastName1 ,
t2.LastName2
FROM ( SELECT DATEPART(YEAR, table1.CreationDate) YEAR ,
DATEPART(MONTH, table1.CreationDate) MONTH ,
COUNT(table1.column2) LastName1
FROM table1
WHERE EventType = 2
AND CreationDate BETWEEN @startdate AND @enddate
GROUP BY DATEPART(YEAR, table1.CreationDate) ,
DATEPART(MONTH, table1.CreationDate)
) AS t1

JOIN

( SELECT DATEPART(YEAR, table2.CreationDate) YEAR ,
DATEPART(MONTH, table2.CreationDate) MONTH ,
COUNT(table2.column2) LastName2
FROM table2
WHERE EventType = 1
AND CreationDate BETWEEN @startdate AND @enddate
GROUP BY DATEPART(YEAR, table2.CreationDate) ,
DATEPART(MONTH, table2.CreationDate)
) AS t2 ON t1.Year = t2.Year
AND t1.Month = t2.Month
ORDER BY t1.Year ,
t1.Month

我可以添加更多的连接吗？(我已经尝试过了，但还是有其他方法可以只返回每个选定列中指定日期范围内的计数(值)。

任何帮助都将不胜感激。

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DECLARE @startdate DATETIME
SET @startdate= '2013-01-02 18:00:21.000';
DECLARE @enddate DATETIME
SET @enddate= '2013-01-09 17:00:21.000';

SELECT YEAR ,
MONTH ,
[1] ,
[2]
FROM ( (SELECT DATEPART(YEAR, CreationDate) YEAR ,
DATEPART(MONTH, CreationDate) MONTH ,
eventType ,
COUNT(LastName) namecount
FROM table1
WHERE CreationDate BETWEEN @startdate AND @enddate
GROUP BY DATEPART(YEAR, CreationDate) ,
DATEPART(MONTH, CreationDate) ,
EventType)
UNION ALL
(SELECT DATEPART(YEAR, CreationDate) YEAR ,
DATEPART(MONTH, CreationDate) MONTH ,
eventType ,
COUNT(LastName) namecount
FROM table2
WHERE CreationDate BETWEEN @startdate AND @enddate
GROUP BY DATEPART(YEAR, CreationDate) ,
DATEPART(MONTH, CreationDate) ,
EventType )
) u PIVOT( SUM(namecount) FOR eventtype IN ( [1], [2] ) ) AS pvt
ORDER BY YEAR ,
MONTH

如果您想添加更多的事件类型，只需添加为([1]、[2]、[3]。)在PIVOT()内，也在SELECT内。

添加任意数量的表。