Question

我正在使用此查询，但我错了...

SELECT * FROM [Orders]
JOIN [Customers]
ON [Orders].[CustomerID] = [Customers].[CustomerID]
WHERE [Orders].[OrderDate] BETWEEN '2010/1/1' AND '2011/1/1'
AND [Orders].[Total] > 1

我收到CustomerID的重复列名称错误。我不确定如何使用Alias来实现这一点。

有人可以告诉我如何正确地写它。

编辑：

感谢所有的建议，这是我可以用的。

SELECT DISTINCT Orders.CustomerID, Orders.ShipToID, Orders.ShipName, Orders.ShipAddress, Orders.ShipAddress2, Orders.ShipCity, Orders.ShipStateOrProvince, Orders.ShipPostalCode, Orders.Total, Orders.OrderDate, Customers.Profession
FROM Orders
JOIN Customers
ON Orders.CustomerID = Customers.CustomerID
WHERE Orders.OrderDate BETWEEN '4/3/2010' AND '2/20/2011'
AND Orders.Total > 1

再次感谢！

Answer 1

SELECT [Orders].* FROM [Orders] ...

仅从Orders表中获取列。或者完全跳过*并明确写出您想要的列。

Answer 2

您需要在开头指定一个表以避免该错误：

SELECT [Orders].* FROM [Orders]

如果您确实需要两个表中的每一列，则必须单独列出它们，并将重复的CustomerID列别名。

SELECT 
    [Orders].CustomerID AS oCustID, 
    [Customers].CustomerID AS cCustID, 
    [Orders].anotherColumn,
    ...

Answer 3

明确您选择的列，而不是SELECT *，并且必须从两个表中获取类似命名的列时，请使用别名。

SELECT
  Orders.OrderID,
  /* alias example, not that you'd need both CustomerID columns */
  Orders.CustomerID AS oCustomerID,
  Customer.CustomerID AS cCustomerID,
  Customers.Name,
  Customers.Address,
  ....
  ....
FROM [Orders]
JOIN [Customers]
ON [Orders].[CustomerID] = [Customers].[CustomerID]
WHERE [Orders].[OrderDate] BETWEEN '2010/1/1' AND '2011/1/1'
AND [Orders].[Total] > 1

Answer 4

您希望引用您想要明确的所有列，而不是使用*。

例如

SELECT 
   C.ID, 
   O.ID 
FROM 
   [Orders] O
   JOIN [Customers] C
     ON O.[CustomerID] = C.[CustomerID]
WHERE 
   O.[OrderDate] BETWEEN '2010/1/1' AND '2011/1/1'
   AND O.[Total] > 1

SQL SELECT重复列

4 个答案: