SQL - “不包含在聚合函数或 GROUP BY 子句中。”

Question

使用 SQL Server 2016。我有一张表：

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

我想计算过去 5 天每件产品的平均数量。我很接近这个查询：

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.

显然我的 OVER 子句有问题，因为当我删除 that 时，我得到了一个有效的结果。

语法上有效的查询（做错事）：

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/指针将不胜感激 - 我很接近，但无法跨越这最后的障碍！

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，外部聚合是不必要的，因为AVG() 被用作窗口函数，而不是聚合函数。

你应该能够在没有子查询的情况下做到这一点：

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“过去五天”解释为当天加上前四天。您的版本平均有六天。