Question

我正在尝试查询我的SQL数据库，以获取每个客户在特定日期范围内下达的订单数量。

我有一份订单清单如下

CustomerName       ClientID        DateOrdered
Customer No.2         10            2011-11-25
Customer No.3         11            2011-10-15
Customer No.3         11            2011-11-25

我希望能够找出特定客户在2011-11-1和2011-11-30之间订了多少订单，这应该会导致：

CustomerName       ClientID        Number
Customer No.3         11             1
Customer No.2         10             1

到目前为止，我已经设法得到了这个

SELECT CustomerName, ClientID, COUNT(*) AS Number      
FROM Orders t     
GROUP BY CustomerName, ClientID      
HAVING COUNT(*) =      
(SELECT MAX(Number)         
FROM          
(SELECT CustomerName, ClientID, COUNT(*) AS Number             
FROM Orders            
GROUP BY CustomerName, ClientID ) x       
WHERE CustomerName = t.CustomerName )

这给了我客户所做的每一笔订单

CustomerName       ClientID        Number
Customer No.3         11             2
Customer No.2         10             1

我是否正确地解决这个问题，或者是否有一种我完全忽视的简单方法！

Answer 1

select CustomerName, ClientID, count(*)
from
(
    select CustomerName, ClientID
    from Orders
    where datediff(mm, DateOrdered, getdate()) <= 1
 )a
group by CustomerName, ClientID

这样做的好处是利用一个子查询来按行给定月份的日期过滤行（这似乎是你要找的东西）。然后按CustomerName和ClientID进行分组，获取订单总和。

Answer 2

应该可以正常工作：

select CustomerName, ClientID, count(*) as Number
from Orders
where DateOrdered between '20111101' and '20111130'
group by CustomerName, ClientID

Answer 3

select ClientID, max(CustomerName), count(*) 
from Orders 
where DateOrdered between '2011-11-01' and '2011-11-30'
group by ClientID

根据数据库的不同，DateOrdered选择的语法可能需要改变。

Answer 4

SELECT
  c.CustomerName,
  count(o.OrderID) as Orders
FROM
  orders o
JOIN clients c ON o.ClientID = c.ClientID
WHERE
  o.DateOrdered BETWEEN '2011-11-01' AND '2011-11-20'
GROUP BY c.ClientID ;

SQL计数日期范围

4 个答案: