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全部，

我有两张表，一张叫员工，另一张叫目标比率。它们通过 FK EmployeeID 关联

tblEmployee
EmployeeID FirstName LastName
1              John     Doe

tblTargetRatio
TargetRatioID EmployeeID EffectiveDate Ratio
      1            1        1/1/2012     8
      2            1        6/1/2012     5
      3            1        9/1/2012     7

我的问题是如何查询 tblTargetRatio 表以返回以下情况的正确记录：

1 EmployeeID = 1 and Date = 03/12/2012 (Expecting Ratio = 8)
2 EmployeeID = 1 and Date = 10/10/2012 (Expecting Ratio = 7)
3 EmployeeID = 1 and Date = 08/12/2012 (Expecting Ratio = 5)

谢谢，艾伦

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1 回答 1

2

您似乎正在寻找最近的生效日期。您可以通过查找小于正在搜索的值的最大值来做到这一点（正在搜索@Date的日期在哪里）：

select top 1 * from tblTargetRatio
where employeeid = 1 and effectivedate < @Date
order by effectivedate desc

演示：http ://www.sqlfiddle.com/#!3/f6d4b/2

于 2012-11-15T22:39:07.713 回答