获取每个不同费率名称的最新费率

Question

RateName     Rate    EffectiveDate
--------     ----    -------------
RateOne      400     2011-01-05
RateOne      410     2011-06-31
RateTwo      147     2010-09-21
RateThree    68      2011-07-14
RateTwo      100     2011-10-30

如果我有上述数据，我如何运行查询以便将这些作为结果：

RateName     Rate    EffectiveDate
--------     ----    -------------
RateOne      410     2011-06-31
RateThree    68      2011-07-14
RateTwo      100     2011-10-30       

基本上，我只需要每个不同费率名称的最新费率。

Answer 1

你可以试试这个：

SELECT A.*
FROM YourTable A
INNER JOIN (    SELECT RateName, MAX(EffectiveDate) AS MaxDate
                FROM YourTable
                GROUP BY RateName) B
ON A.RateName = B.RateName AND A.EffectiveDate = B.MaxDate