Question

使用SQL Server2016。我有一个表：

Product   Qty   OrderDate
--------------------------
Toys      100   2018-10-01
Toys      100   2018-10-01
Books      30   2018-10-01
Toys      150   2018-10-02
Toys       50   2018-10-02
Toys       20   2018-10-02
Toys      110   2018-10-03
Toys       90   2018-10-04
Toys      200   2018-10-05
Toys      100   2018-10-05
Toys       30   2018-10-08
Toys       50   2018-10-09

，我想计算最近5天每种产品的平均数量。这个查询与我很接近：

SELECT 
  Product,
  RowNumber, 
  OrderDate, 
  AVG(TotalQty) OVER (ORDER BY RowNumber DESC ROWS 5 PRECEDING) as RollingAvg
FROM 
(
SELECT ROW_NUMBER() OVER (PARTITION BY Product ORDER BY orderDate) AS RowNumber, Product, OrderDate, sum(Qty) as TotalQty
  FROM Tbl 
  GROUP BY Product, OrderDate
) x
GROUP BY Product, RowNumber, OrderDate

内部查询正常工作，为我提供每个产品/日期对的总数。但是我的外部查询报告了一个问题：

Column 'x.TotalQty' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause.

我的OVER子句显然出了问题，因为当我删除那个时，我得到了一个有效的结果。

语法上有效的查询（做错了事）：

SELECT 
  Product,
  RowNumber, 
  OrderDate, 
  AVG(TotalQty) as RollingAvg
FROM 
(
SELECT ROW_NUMBER() OVER (PARTITION BY Product ORDER BY orderDate) AS RowNumber, Product, OrderDate, sum(Qty) as TotalQty
  FROM Tbl 
  GROUP BY Product, OrderDate
) x
GROUP BY Product, RowNumber, OrderDate

任何帮助/指针都将不胜感激-我很亲密，但不能越过最后的关卡！

Answer 1

我想你想要

SELECT Product, RowNumber, OrderDate, 
       AVG(TotalQty) OVER (ORDER BY RowNumber DESC ROWS 5 PRECEDING) as RollingAvg
FROM (SELECT ROW_NUMBER() OVER (PARTITION BY Product ORDER BY orderDate) AS RowNumber,
             Product, OrderDate, sum(Qty) as TotalQty
      FROM Tbl 
      GROUP BY Product, OrderDate
     ) x;

也就是说，不需要外部聚合，因为AVG()被用作窗口函数，而不是聚合函数。

您应该能够在没有子查询的情况下执行此操作：

SELECT ROW_NUMBER() OVER (PARTITION BY Product ORDER BY orderDate) AS RowNumber,
       Product, OrderDate, sum(Qty) as TotalQty,
       AVG(SUM(Qty)) OVER (PARTITION BY Product ORDER BY orderDate ROWS BETWEEN 4 PRECEDING AND CURRENT ROW) as avg_5
FROM Tbl 
GROUP BY Product, OrderDate;

请注意，这会将“最后五天”解释为当前日期加上前四天。您的版本平均需要六天的时间。

SQL-“既不包含在聚合函数中，也不包含在GROUP BY子句中。”

1 个答案: