如何根据临时 table SQL Server 2008 R2 从一个 table 中提取数据？

Question

我目前的查询：

SELECT   
    E.FILEKEY,
    (SELECT MAX(EFFDATE) 
     FROM
         (SELECT B.FILEKEY, B.STATUS AS STATUS, B.EFFDATE 
          FROM TABLEB B
          UNION
          SELECT A.FILEKEY, A.STATUS2 AS STATUS, A.EFFDATE2 AS EFFDATE 
          FROM TABLEA A) C
     WHERE C.EFFDATE <= '5/1/2011'),   
    A.STATUS
FROM 
    TABLE1 A 
INNER JOIN 
    TABLE2 B ON A.FILEKEY = B.FILEKEY
GROUP BY 
    A.FILEKEY, A.STATUS

tableA 和 tableB (table C) 的并集产生这些结果：

FILEKEY STATUS  EFFDATE
----------------------------------------
1          0    2009-01-01 00:00:00.000
1          1    2010-01-01 00:00:00.000
1          0    2011-01-01 00:00:00.000
1          1    2012-01-01 00:00:00.000
1          0    2013-01-01 00:00:00.000

我知道我的查询是错误的，得出以下结果：

filekey  (No column name)           status
------------------------------------------
1         2011-01-01 00:00:00.000     1

我只是不确定如何使用关联的 effdate 提取正确的状态，而不会导致出现各种错误。

感谢您的帮助。

Answer 1

我想你正在寻找这样的东西。

SELECT TOP 1 *
FROM
     (SELECT B.FILEKEY, B.STATUS AS STATUS, B.EFFDATE FROM TABLEB B
      UNION
      SELECT A.FILEKEY, A.STATUS2 AS STATUS, A.EFFDATE2 AS EFFDATE FROM TABLEA A) C
WHERE C.EFFDATE <= '5/1/2011')
ORDER BY C.EFFDATE DESC

如何根据临时 table SQL Server 2008 R2 从一个 table 中提取数据？

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sql

sql-server-2008-r2