Question

我正在努力完成以下任务：

SELECT 
   *,
   CASE WHEN 1 THEN SUM(b.myField) ELSE AVG(b.myField) END OVER (PARTITION BY ID)
FROM tbl a
LEFT JOIN tbl2 b ON a.ID = b.aID

这是否可以使用SQL Server中的窗口函数？

我可以在没有case语句的情况下完成以下操作：

SELECT 
   *,
   SUM(b.myField) OVER (PARTITION BY ID)
FROM tbl a
LEFT JOIN tbl2 b ON a.ID = b.aID

Answer 1

你可以试试这个：

SELECT 
   *,
   CASE WHEN (SUM(b.myField) 
OVER (PARTITION BY ID))=1 THEN SUM(b.myField)
 ELSE AVG(b.myField) END 
FROM tbl a
LEFT JOIN tbl2 b ON a.ID = b.aID

Answer 2

你可以这样做

SELECT *, CASE 
    [something]
    WHEN 1 THEN SUM(myfield) OVER (PARTITION BY ID) 
    ELSE AVG(myfield) OVER (PARTITION BY ID) END 
FROM yourtable

我不确定你应该这样做，不过

Answer 3

我认为您需要将其包装在cte中以获得独特的结果：

CREATE TABLE #temp (ID INT, myField DECIMAL(6,2))
INSERT INTO #temp
        ( ID, myField )
VALUES  ( 1,1 ),(1,2),(1,3),(1,4),(2,2),(2,10),(3,4),(4,4),(4,2)

;WITH cte AS (SELECT  ID ,
        CASE WHEN ID = 1 THEN AVG(MyField) OVER ( PARTITION BY ID )
             ELSE SUM(MyField) OVER ( PARTITION BY ID )
        END AS SumOrAvg
FROM #temp)

SELECT DISTINCT ID, SumOrAvg
FROM cte

DROP TABLE #temp

在窗口函数中使用Case（OVER（Partition））

3 个答案: