具有两个具有引用键的表的sql查询

我有两张桌子：

Discounts(disid primary key)

Cust(custid primary key, disid ref discount(disid))

---

现在，我需要一个查询来获取拥有所有

disid

（折扣券）的

custid

，并且客户可能多次包含相同的

disid

。

尝试以下任一解决方案：

select custid, count(distinct disid) from cust
group by custid
having count(*) = (select count(*) from discounts)

SELECT  a.custid, COUNT(a.disid) totalCoupon
FROM    cust a  
            INNER JOIN discounts b 
                ON b.disid = a.disid 
GROUP BY a.custid

或

---

请尝试以下任一解决方案：

SELECT  a.custid, COUNT(a.disid) totalCoupon
FROM    cust a  
            INNER JOIN discounts b 
                ON b.disid = a.disid 
GROUP BY a.custid

或

---

一个简单的连接就不行了？如果没有更多的信息需要一个简单的加入不会做吗？如果没有更多的信息需要

SELECT  a.custid, COUNT(a.disid) totalCoupon
FROM    cust a  
            INNER JOIN discounts b 
                ON b.disid = a.disid 
GROUP BY a.custid
HAVING   COUNT(a.disid) > 1 -- customers having the same (but more than 1) 
                            -- CouponID will only be shown here