Question

我有一个存储客户销售日期的表格如下：

|CustomerId|SalesDate |Product|Price|
|1         |2015-01-01|A      | 5.00|
|1         |2015-02-01|A      |10.00|
|1         |2015-03-01|B      | 7.00|
|2         |2015-01-15|A      | 9.00|

我想为购买产品A的每位客户选择一行。如果客户多次购买产品A，我只想查看最近购买的商品。

这是所需的输出：

|CustomerId|SalesDate |Product|Price|
|1         |2015-02-01|A      |10.00|
|2         |2015-01-15|A      | 9.00|

我已经尝试了不同版本的群组/通过这样的查询：

SELECT CustomerId, SalesDate, Product, Price
FROM Sales
WHERE Product = 'A'
GROUP BY CustomerId
HAVING MAX(SalesDate);

Answer 1

只需在select语句中获取销售日期的最大值。

select customerid, max(salesdate) as salesdate, 'A'
from sales
where product = 'A'
group by customerid

有新要求

select customerid, maxsalesdate, Product, Price
from sales
join (select customerid, max(salesdate) as maxsalesdate
      from sales
      where product = 'A'
      group by customerid) as sub on 
        sub.customerid = sales.customerid and 
        sub.maxsalesdate = sales.salesdate
where product = 'A'

Answer 2

使用join和聚合：

执行此操作

select s.*
from sales s join
     (select customerid, max(salesdate) as salesdate
      from sales s
      where product = 'A'
      group by customerid
     ) cs
     on s.customerid = cs.customerid and s.salesdate = cs.salesdate
where s.product = 'A';

汇总获取每个客户的最长销售日期。 join选择与该信息匹配的行。

选择最近的不同客户行

2 个答案: