Question

我正在研究Datacamp T-SQL课程，由于某种原因，我不知道要使用数据透视表。

开始查询是：

SELECT CategoryID, AVG(UnitPrice) AS Price
FROM Products
GROUP BY CategoryID;

结果是：

CategoryID     Price      
----------------------
1              37.9791
2              23.0625
3              25.1600
4              28.7300
5              20.2500
6              54.0066
7              32.3700
8              20.6825

我想要的结果

Per Category        1       2       3       4       5       6       7       8
Average Unit Price  37.98   23.06   25.16   28.73   20.25   54.01   32.37   20.68

我写的代码：

SELECT * 
FROM
    (SELECT CategoryID, AVG(UnitPrice)
     FROM DBO.Products) AS test
PIVOT 
    (UnitPrice 
     FOR CategoryID IN ([1], [2], [3], [4], [5], [6], [7], [8])) AS PivotTable
GROUP BY 
    CategoryID

但是然后我得到了错误

[42000] [Microsoft] [SQL Server的ODBC驱动程序17] [SQL Server]关键字'FOR'附近的语法不正确。（156）（SQLExecDirectW）

我还尝试了枢轴上的AVG(UnitPrice)。

然后生成此错误：

[42S22] [Microsoft] [SQL Server的ODBC驱动程序17] [SQL Server]无效的列名'UnitPrice'。（207）（SQLExecDirectW）

我已经在这上面呆了一段时间了，我也不知道在哪里看。如果有人可以指出正确的方向，请先谢谢。

Answer 1

假设Products中的列多于所示的列，我认为您想要这样做：

SELECT * FROM
(SELECT CategoryID, UnitPrice
FROM DBO.Products) as test
PIVOT (
     AVG(UnitPrice) FOR
     CategoryID IN ([1], [2], [3], [4], [5], [6], [7], [8])
) AS PivotTable

PIVOT隐藏了一个不需要重复的显式分组。如果Products仅包含CategoryID和UnitPrice，我们可以直接使用它，而不是test子查询

Answer 2

我将删除GROUP BY：

SELECT * 
FROM (SELECT CategoryID, UnitPrice FROM DBO.Products) as test
PIVOT (AVG(UnitPrice) FOR CategoryID IN ([1], [2], [3], [4], [5], [6], [7], [8])
      ) AS PivotTable

Answer 3

SELECT  CategoryID, [1], [2], [3], [4], [5], [6], [7], [8] FROM 

(SELECT price, CategoryID from dbo.Products) x 

PIVOT (
 MAX(price) FOR
 CategoryID IN ([1], [2], [3], [4], [5], [6], [7], [8])
) AS PivotTable

Answer 4

这有效：

SELECT 'Average Unit Price' AS 'Per Category',   
[1], [2], [3], [4], [5], [6], [7], [8]
FROM  
(SELECT CategoryID, UnitPrice   
    FROM dbo.Products) AS SourceTable  
PIVOT  
(  
AVG(UnitPrice)  
FOR CategoryID IN ([1], [2], [3], [4], [5], [6], [7], [8])
) AS PivotTable;

关键字“ FOR”附近的T-SQL Pivot错误语法

4 个答案: