SQL（使用select语句进行内部联接）

Question

我有2张桌子拍卖和客户

拍卖

custId|itemName|yearsUsed|bidPrice
   1  | MacBook|    2    |  1500
   3  |  Dell  |    1    |  1000
   2  | MacBook|    2    |  1500

顾客

 custId|custName
   1   | tom
   2   | jerry
   3   | susan

我想查询那些为某个项目出价相同价格的客户名称，项目名称和出价以及所有者使用的年份

以下查询返回客户具有相同出价价格的商品名称

  SELECT ac.itemName,
         ac.yearsUsed,
         ac.bidPrice 
    FROM auction ac 
GROUP BY ac.itemName,
         ac.yearsUsed,
         ac.bidPrice 
  HAVING COUNT(*) > 1;

产量

itemName yearsUsed  bidPrice
----------------------------
 MacBook     2       1500

现在，我想查询对该商品出价相同价格的客户名称

  SELECT ac.itemName,
         ac.yearsUsed,
         ac.bidPrice 
    FROM auction ac 
         INNER JOIN (
                     SELECT custName 
                       FROM customer
                    ) c 
               ON c.custId = ac.custId 
GROUP BY ac.itemName,
         ac.yearsUsed,
         ac.bidPrice 
  HAVING COUNT(*) > 1;

我得到一个错误

ERROR at line 1:
ORA_00904:"C"."CUSTID": invalid identifier

我正在使用sqlplus

Answer 1

您必须在内部查询中添加custid 。

SELECT 
  ac.itemName,
  ac.yearsUsed,
  ac.bidPrice 
FROM 
 auction ac INNER JOIN
    (SELECT custName,
      -- The following CUSTID was missing:
     CUSTID 
     FROM customer) c ON c.custId = ac.custId 
GROUP BY ac.itemName,ac.yearsUsed,ac.bidPrice 
HAVING COUNT(*) > 1;

但是 ，根据您的情况， 子查询不是必需的。

SELECT 
  ac.itemName,
  ac.yearsUsed,
  ac.bidPrice 
FROM 
 auction ac INNER JOIN
 customer c ON c.custId = ac.custId 
GROUP BY 
   ac.itemName,
   ac.yearsUsed,
   ac.bidPrice 
HAVING COUNT(*) > 1;

如果您还需要根据评论添加客户的姓名，则需要使用解析表达式count(*) over(...) ：

select
  custName,
   itemName,
   yearsUsed,
   bidPrice
from (
  SELECT 
    c.custName,
    ac.itemName,
    ac.yearsUsed,
    ac.bidPrice,
    count(*) over (partition by 
                   ac.itemName, 
                   ac.yearsUsed, 
                   ac.bidPrice) cnt
  FROM 
   auction ac INNER JOIN
   customer c ON c.custId = ac.custId 
)
where
  cnt > 1

另请参见此SQL提琴

Answer 2

这样尝试

     SELECT 
ac.itemName,
ac.yearsUsed,
ac.bidPrice,
c.custName
 FROM auction ac 
LEFT JOIN customer c ON c.custId = ac.custId 
GROUP BY ac.itemName,ac.yearsUsed,ac.bidPrice 
HAVING COUNT(*) > 1;

Answer 3

内部select缺少cust_id 。 为什么要使用内部select ？

select ac.itemname
,      ac.yearsused
,      ac.bidprice
from   auction ac
inner
join   customer c
on     c.custid = ac.custid
group
by     ac.itemname
,      ac.yearsused
,      ac.bidprice
having count(*) > 1
;