Question

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custid所有disid（折扣优惠券），并且客户可能会多次包含相同的disid。

Answer 1

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

Answer 2

SELECT COUNT(DISTINCT D.disid) FROM CUST C 
INNER JOIN DISCOUNTS D ON D.disid=C.disid GROUP BY D.disid

Answer 3

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

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

带有两个具有引用键的表的SQL查询

3 个答案: