Date Access-如何计算订单之间的平均天数（无光标）

我想在access中创建一个查询，返回订单之间的平均天数。 表格结构为： 表名：

表列：

对表的简单查询将返回以下内容：

1 1131 01/01/2015 $235
2 1145 02/01/2015 $11
3 1131 03/01/2015 $256
4 1131 04/01/2015 $300
5 1146 05/01/2015 $25
6 1145 10/01/2015 $15
7 1145 20/01/2015 $4
8 1131 21/01/2015 $45

在这个例子中

client 1131 has orders on the days: 01/01/2015; 03/01/2015; 04/01/2015; 21/01/2015
client 1145 has orders on the days: 02/01/2015; 10/01/2015; 20/01/2015
client 1146 has orders on days: 05/01/2015

我想为每个客户创建一个查询，返回订单之间的平均天数：

1131 5
1145 6
1146 null

如果是sql server，我会使用游标，但在Access中，我不知道如何操作

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有什么帮助吗？

在SQL Server中不需要光标。 话虽如此，请尝试下面的查询。 如果客户下了一个订单，逻辑上结果应该是0，而不是null。 Null应反映未下订单的任何客户

SELECT Orders.idClient, (Max(Orders.OrderDate)-Min(Orders.OrderDate))/Count(*) AS [Days between orders]
FROM Orders
GROUP BY Orders.idClient

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在SQL Server中不需要游标。 话虽如此，请尝试下面的查询。 如果客户下了一个订单，逻辑上结果应该是0，而不是null。 Null应反映未下订单的任何客户

SELECT Orders.idClient, (Max(Orders.OrderDate)-Min(Orders.OrderDate))/Count(*) AS [Days between orders]
FROM Orders
GROUP BY Orders.idClient

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创建如下查询：

Select
    idClient,
    Avg(DaysPast) As AverageOrderDays
From    
    (Select 
        idClient, 
        DateDiff("d",
                (Select Max(T.[Purchase Week]) 
                From Orders As T 
                Where T.idClient=Orders.idClient 
                And T.[Purchase Week] < Orders.[Purchase Week]),
            [Purchase Week]) AS DaysPast
    From 
        Orders) As OrderDays
Group By
    idClient

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创建如下查询：

Select
    idClient,
    Avg(DaysPast) As AverageOrderDays
From    
    (Select 
        idClient, 
        DateDiff("d",
                (Select Max(T.[Purchase Week]) 
                From Orders As T 
                Where T.idClient=Orders.idClient 
                And T.[Purchase Week] < Orders.[Purchase Week]),
            [Purchase Week]) AS DaysPast
    From 
        Orders) As OrderDays
Group By
    idClient

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作为参考，Access VBA中稍微等效的是一个记录集。作为参考，Access VBA中稍微等效的是一个记录集。感谢Rene，它似乎工作正常。所以，神奇之处在于执行maxorders.date-min orders.date/count*并按客户机分组；我说的对吗？谢谢你，雷内，它看起来很好用。所以，神奇之处在于执行maxorders.date-min orders.date/count*并按客户机分组；我说得对吗？