Question

我一直遇到问题。我需要得到的是AVERAGE率最高的前3个国家。

SELECT TOP 3 
   Country, AVG(AverageRate) AS 'AverageRate'
FROM 
   dbo.CountryOrders
WHERE 
   OrderDate BETWEEN '2011-01-01' AND '2011-12-31'
GROUP BY 
   Country
ORDER BY 
   'AverageRate' DESC;
GO

Answer 1

问题是单引号是AverageRate。仅对字符串和日期常量使用单引号。你在这里不需要它们，所以只需删除它们：

SELECT  TOP 3 Country, AVG(AverageRate) AS AverageRate
FROM dbo.CountryOrders
WHERE OrderDate BETWEEN '2011-01-01' AND '2011-12-31'
GROUP BY Country
ORDER BY AverageRate DESC;

您通过一个常量值（字符串'AverageRate'）排序查询失败。如果需要转义标识符，请使用双引号或方括号（Sybase和SQL Server特定的）。

Answer 2

这应该有效：

SELECT  TOP 3 Country, AVG(AverageRate) AS 'AverageRate'
FROM dbo.CountryOrders
WHERE OrderDate BETWEEN '2011-01-01' AND '2011-12-31'
GROUP BY Country
ORDER BY AVG(AverageRate) DESC;
GO

SQL协助：查询问题

2 个答案: