Sql join解決方案是否適用於以下情況？

Question

我們可以解決以下情況下與加入，我已經和窗口功能解決

關係：在下面的表中，Orders表中的每一個訂單，與給定的客戶通過引用ID中的cust_id外鍵列相關客戶表中的列。

問題：查找每個銷售員和相關訂單號以及該訂單所屬的客戶和銷售人員姓名的最大訂單金額。

Create Table Salesperson 
(
    ID   int, 
    name  varchar(100), 
    age   float, 
    salary  money 
); 

Create Table Orders 
(
    Number   int, 
    order_date  datetime, 
    cust_id   int,  
    salesperson_id int, 
    Amount   money 
); 

Create Table Customer 
(
    ID    int, 
    name   varchar(100), 
    city   varchar(100), 
    IndustryType varchar(100) 
); 

insert into Salesperson values 
(1,'Rohit',25,50000), 
(2,'Pramod',25,50000), 
(3,'Atul',25,50000); 

insert into Orders values 
(1,getdate(),101,1,50000), 
(2,getdate(),101,1,500000), 
(3,getdate(),102,1,10000), 
(4,getdate(),101,2,5000), 
(5,getdate(),102,2,700000), 
(6,getdate(),102,2,10000); 

insert into Customer values 
(101,'Altu','bhopal','IT'), 
(102,'bltu','bhopal','ITES'), 
(103,'cltu','bhopal','NW'); 

解決方案與窗函數：

with CTE_MaxAmount 
as 
(
    select max(amount) over (partition by salesperson_id) as amount, 
      dense_rank() over (partition by salesperson_id order by amount) as rowid, 
      cust_id, 
      salesperson_id,number 
    from Orders with(nolock) 
) 
select ct.amount, 
     ct.cust_id, 
     c.name as customername, 
     s.name as salesman, 
     ct.salesperson_id, 
     number as OrderNumbner 
from Customer c 
join CTE_MaxAmount ct 
on  (c.id = ct.cust_id) 
join Salesperson s 
on  (s.id = ct.salesperson_id) 
where rowid = 1; 

Answer 1

我和我個人的政策是不會回答的家庭作業的問題，因爲這個問題是要表明英語是多麼容易轉化爲SQL機會打破。問題與查詢可以建立完全一致。

找到最大的訂單金額爲每個銷售人員

select max(Amount) as Amount, salesperson_id from Orders group by salesperson_id 

，並與客戶一起相關的訂單號

select o.Number, M.salesperson_id, M.Amount 
from Orders as o join (
    select max(Amount) as amount, salesperson_id 
    from Orders group by salesperson_id 
) as M 
on o.salesperson_id = M.salesperson_id 
and o.Amount = M.Amount 

select c.name, o.Number, M.salesperson_id, M.Amount 
from Orders as o join (
    select max(Amount) as amount, salesperson_id 
    from Orders group by salesperson_id 
) as M 
on o.salesperson_id = M.salesperson_id 
and o.Amount = M.Amount 
join Customer as c 
on o.cust_id = c.ID 

和銷售人員的姓名

select s.name as 'salesperson', 
c.name as 'customer', 
o.Number, M.salesperson_id, M.Amount 
from Orders as o join (
    select max(Amount) as amount, salesperson_id 
    from Orders group by salesperson_id 
) as M 
on o.salesperson_id = M.salesperson_id 
and o.Amount = M.Amount 
join Customer as c 
on o.cust_id = c.ID 
join Salesperson as s 
on o.salesperson_id = s.ID