从SQL Server中的另一个表转换数据后更新表？

Question

我有两个表，我想用两个表中日期相等的另一个表的列更新一个表的列。这里的问题是两个表中的日期不同。

SELECT UploadedDateTime = LEFT(CAST(UploadedDateTime AS DATETIME), 11),
        COUNT(DISTINCT ClientID) AS 'DocsCount' 
FROM ClientUploadedTaxDocuments
WHERE CONVERT(DATETIME, CONVERT(NVARCHAR(10), UploadedDateTime, 101)) > '1/1/2014' 
GROUP BY LEFT(CAST(UploadedDateTime AS DATETIME), 11)
ORDER BY LEFT(CAST(UploadedDateTime AS DATETIME), 11) 

以上查询的输出是，

1 ..

从FilesReceivedReport

中选择*

2 ..

这里我想用DocsCount（第1表的列）更新Y2014（第2表的列），其中日期相等。

由于

Answer 1

首先，给第一个选定的列一些好名字。添加“AS日期”，它变为

SELECT UploadedDateTime = LEFT(CAST(UploadedDateTime AS DATETIME), 11) AS 'Date',
    COUNT(DISTINCT ClientID) AS 'DocsCount' 
FROM ClientUploadedTaxDocuments
WHERE CONVERT(DATETIME, CONVERT(NVARCHAR(10), UploadedDateTime, 101)) > '1/1/2014' 
GROUP BY LEFT(CAST(UploadedDateTime AS DATETIME), 11)
ORDER BY LEFT(CAST(UploadedDateTime AS DATETIME), 11) 

然后，尝试这样的事情：

UPDATE f set Y2014 = s.DocsCount FROM FilesReceivedReport AS f
INNER JOIN (your_complicated_select) AS s
ON f.D == s.Date