Question

可能重复：
Writing an SQL query to SELECT item from the following table

我正在尝试列出至少有两个不同部件的供应商的供应商名称（sname）和部件号（pnum）。

以下是我需要使用的两个表...

我尝试了什么：

这是不正确的，我沿着这些方向试了一下......

SELECT snum 
FROM (SELECT snum, count(snum) AS nbr FROM Shipments ) 
WHERE nbr > 1;

谢谢

Answer 1

SELECT suppliers.sname, shipments.pnum
FROM suppliers, shipments
WHERE shipments.snum = suppliers.snum
GROUP BY suppliers.sname
HAVING count(shipments.pnum) >= 2

Answer 2

使用COUNT等聚合函数时，需要使用GROUP BY子句。使用Aggregates和GROUP BY时，HAVING CLAUSE充当您的where子句。

这将为您提供所有具有计数＆gt;的snums 1

SELECT snum
FROM
(
    SELECT snum, count(snum) AS nbr
    FROM Shipiments
    GROUP BY snum
    HAVING COUNT(snum) > 1
) AS T

这会将表格连接到供应商表格以获取供应商名称

SELECT DISTINCT Suppliers.sname
FROM
(
    SELECT snum, count(snum) AS nbr
    FROM Shipiments
    GROUP BY snum
    HAVING COUNT(snum) > 1
) AS T INNER JOIN Suppliers ON Suppliers.snum = T.snum

Answer 3

我不知道Access（因为这个问题被标记为这样），但这应该适用于MySQL：

select su.sname from suppliers su
join shipments sh on su.snum = sh.snum
group by su.sname
having count(distinct su.pnum) >= 2

无法为下表编写SELECT查询

3 个答案: