Question

我想计算客户曾经拥有的所有订单的订单明细行总数。

这是我的查询

SELECT SUM(
           (SELECT count(*) 
            FROM dbo.Order_Details 
            WHERE dbo.Order_Details.OrderID = dbo.Orders.OrderID))
    FROM dbo.Orders
    WHERE dbo.Orders.CustomerID = "123"

SQL Server给我一个错误“无法对包含聚合或子查询的表达式执行聚合函数。”

对此有任何帮助将不胜感激。

Answer 1

SELECT COUNT(*)
FROM Orders
    INNER JOIN Order_Details ON Orders.OrderID = Order_Details.OrderID
WHERE Orders.CustomerID = "123"

Answer 2

你不需要sum（），因为count（*）已经为你提供了总数。

SELECT (SELECT count(*) 
    FROM dbo.Order_Details 
    WHERE dbo.Order_Details.OrderID = dbo.Orders.OrderID)
FROM dbo.Orders
WHERE dbo.Orders.CustomerID = "123"

Answer 3

不应该只是：

SELECT count(*) FROM dbo.Order_Details, dbo.Orders 
 WHERE dbo.Order_Details.OrderID = dbo.Orders.OrderID
 AND dbo.Orders.CustomerID = "123"

Answer 4

Count（*）正在为你做总结。只需从表达式中删除SUM聚合。

Answer 5

我认为以下内容应该做你想做的事情：

select count(1) from dbo.order_details d
join dbo.orders o on d.OrderId=o.OrderId
where dbo.orders.CustomerID="123"

Answer 6

以下假设您在Order_Details表中有一个名为OrderDetailID的列。如果没有，只需替换订单明细记录的唯一标识符。

SELECT COUNT(DISTINCT OD.OrderDetailID)
FROM Orders O
  LEFT JOIN Order_Details OD on (OD.OrderId = O.OrderId)
WHERE O.CustomerID = "123"

需要有关SQL子查询的帮助

6 个答案: