在Sql server 2012里面,开窗函数丰富了许多,其中带出了2个新的函数 First_Value 和 Last Value .现在来介绍一下这2个函数的应用场景.首先分析一下First_Value(),用法是根据Partition By对数据进行分区,如果忽略Partit ...
在Sql server 2012里面,开窗函数丰富了许多,其中带出了2个新的函数 First_Value 和 Last Value .现在来介绍一下这2个函数的应用场景.
首先分析一下First_Value(),用法是根据Partition By对数据进行分区,如果忽略Partition By ,那么默认整块数据一个区域,然后根据Order By 进行排序,取出第一个值。
;WITH CTE AS(SELECT 1 AS ID ,'2016-06-01' AS DT,'A' AS UName,135 AS TotalAmount UNION ALLSELECT 2 AS ID ,'2016-06-05' AS DT,'A' AS UName,148 AS TotalAmount UNION ALLSELECT 3 AS ID ,'2016-06-02' AS DT,'B' AS UName,120 AS TotalAmount UNION ALLSELECT 4 AS ID ,'2016-06-06' AS DT,'B' AS UName,153 AS TotalAmount UNION ALLSELECT 5 AS ID ,'2016-06-10' AS DT,'B' AS UName,198 AS TotalAmount )SELECT * , FIRST_VALUE(CTE.TotalAmount) OVER (PARTITION BY CTE.UName ORDER BY CTE.ID) AS FirstDeal, FIRST_VALUE(CTE.DT) OVER (PARTITION BY CTE.UName ORDER BY CTE.ID) AS FirstDate FROM CTE
ID DT UName TotalAmount FirstDeal FirstDate
原标题:开窗函数 First_Value 和 Last_Value
关键词:函数
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