Question

我可能有一个非常简单的问题，但似乎我无法找到解决方案。基本上，我必须编写一个基于Northwind DB的SQL-Server函数。它必须：

将2个日期作为参数并显示，而不是重复这些客户数据ID | Name | City | Address，对于那些客户，其中至少购买了一次员工，大于此员工在两个日期之间的平均销售额。

所以主要步骤应该是：
1.从每个员工中检索客户的总购买量。我知道如何从每个公司获得总购买量：

SELECT Customers.CompanyName, SUM(UnitPrice*Quantity) FROM Orders inner join [Order Details] ON Orders.OrderID=[Order Details].OrderID INNER JOIN Customers ON Orders.CustomerID=Customers.CustomerID GROUP BY Customers.CompanyName

但我如何从每位员工那里获得这些？

2.在给定日期之间与此员工的平均销售额对应。我可以得到每个员工的平均值：

SELECT FirstName+' '+LastName, AVG(UnitPrice*Quantity) FROM Orders inner join [Order Details] ON Orders.OrderID=[Order Details].OrderID INNER JOIN Employees ON Orders.EmployeeID=Employees.EmployeeID WHERE OrderDate BETWEEN @dt1 and @dt2 GROUP BY FirstName+' '+LastName

请注意，我只粘贴查询部分，但在这里，Employee应该依赖于第一个查询（可能这应该放在子查询中）

所有东西都应该放在一个单独的功能中（不应该分成两部分）。 Northwind DB图是：Northwind Diagram。请帮忙！

Answer 1

希望我的逻辑是正确的：

create function x (@from datetime, @to datetime)
returns table
as
return (
    with cust as (
        select o.customerid, o.employeeid, sum(unitprice*quantity) as cust_purchase
        from orders o
        inner join [order details] d on o.orderid=d.orderid
        where o.orderdate between @from and @to
        group by o.customerid, o.employeeid
    ),
    emp as (
        select o.employeeid, avg(unitprice*quantity) as emp_sale
        from orders o
        inner join [order details] d on o.orderid=d.orderid
        where o.orderdate between @from and @to
        group by o.employeeid
    )
    select c.customerid, c.companyname, c.city, c.address
    from cust
    inner join emp on cust.employeeid = emp.employeeid
    and cust.cust_purchase > emp.emp_sale
    inner join customers c on cust.customerid = c.customerid
)
go

select * from x ('19980401', '19980430')

SQL-Server，面对具有Employees功能的客户

1 个答案: