Question

我有2个表，例如Customers和Purchases表。而且我试图让那些在某一年内购买超过1件的顾客。所以这是我当前的查询

select c.name, c.email
from customers c inner join purchases p
    on c.customerid = p.customerid
where p.year = 2002
    group by c.name, c.email

我现在遇到的问题是这个查询会导致任何购买的人不是我想要的。所以我想编辑为：

select c.name, c.email
from customers c inner join purchases p
    on c.customerid = p.customerid
where p.year = 2002 and p in
    (select p.customerid, count(p.*) as total
    from purchases
    where total > 1
        group by p.customerid)
    group by c.name, c.email

此查询已完整语法错误。有人帮我问一个想法。

Answer 1

可能是这样的

SELECT C.Name, C.Email
FROM Customers C INNER JOIN Purchases P ON C.CustomerID = P.CustomerID
WHERE P.Year = 2002
GROUP BY C.Name, C.Email
HAVING COUNT(P.CustomerID) > 1

Answer 2

SELECT *
FROM Customers
WHERE (SELECT COUNT(*)
       FROM Purchases
       WHERE Year = 2002
         AND CustomerID = Customers.CustomerID) > 1

用group by获取聚合值的正确方法

2 个答案: