Question

我有一个产品，供应商和prdtFrn表，如下所示：

suppliers:
 fid , name
   1 | 'Andrey' 
   2 | 'lucas'

products:
 pid , name
   1 | 'X' 
   2 | 'Y' 

prdtFrn:
 pid , fid , price
  ---------------- supplier 'andrey'
   1 |  1  | 19.00 
   2 |  1  | 16.00 
  ----------------- supplier 'lucas'
   1 |  2  | 14.00 
   2 |  2  | 18.00

我正在寻找一个SQL查询，它将 返回以低于 我的价格出售的所有产品（andrey）。在这个例子中，我想获得产品“X”，因为卢卡斯以低于我的价格出售它。

Answer 1

许多其他答案似乎很复杂，但答案很简单：

select distinct p1.* 
from prdtfrn p1
join prdtfrn p2 on p1.pid = p2.pid and p2.fid != 1 and p2.price < p1.price
where p1.fid = 1; // fid=1 is known to be 'Audrey'

此查询列出了其他地方销售更便宜的所有产品。

Answer 2

只需从prdtFrn表中选择两次。从那里，查询很简单。

我在下面列出了一个未经测试的示例。 A对应于竞争对手的产品，B对应于您的产品。

SELECT 
    suppliers.name, 
    A.pid, 
    A.price 
FROM 
    prdtfrn AS A, 
    prdtfrn AS B, 
    suppliers 
WHERE 
    A.price < B.price
    AND A.pid = B.pid
    AND B.fid = 1
    AND A.fid = suppliers.fid;

Answer 3

我认为您正在与许多供应商（ 不仅仅是lucas ）进行比较，所以这是我的查询。试试这个：

SELECT  e.name,
        g.name,
        f.price
FROM suppliers e INNER JOIN prdtFrn f ON
        e.fid = f.fid
     INNER JOIN products g ON
        f.pid = g.pid
WHERE   e.name <> 'Andrey' AND  -- this selects all products which is not yours
        f.pid IN                -- the selected products should match your products
            (SELECT c.pid       -- this subquery selects all your products
                    c.name,     
                    b.price
            FROM suppliers a INNER JOIN prdtFrn b ON
                    a.fid = b.fid
                 INNER JOIN products c ON
                    b.pid = c.pid
            WHERE  a.name = 'Audrey') d AND
        f.price < d.price       -- product is less than yours

Answer 4

这是一个获取您正在寻找的信息的查询。由于可能有其他供应商出售的产品而您没有，我认为您可能也有兴趣找到它们。

这是您要求的查询（没有其他供应商提供的产品，您没有）：

select sp2.pid, p.name as ProductName, sp2.price, s2.name as SupplierName
from prdtFrn sp2 join (
  select sp.pid, sp.price from suppliers s
  join prdtFrn sp on sp.fid = s.fid
  where s.name = 'Andrey'
) as AndreysProducts
on AndreysProducts.pid = sp2.pid
join products p on sp2.pid = p.pid
join suppliers s2 on s2.fid = sp2.fid
where sp2.price < AndreysProducts.price

Example

这是您可能感兴趣的查询（使用其他供应商提供的产品，但您没有）：

select sp2.pid, p.name as ProductName, sp2.price, s2.name as SupplierName
from prdtFrn sp2 left join (
  select sp.pid, sp.price from suppliers s
  join prdtFrn sp on sp.fid = s.fid
  where s.name = 'Andrey'
) as AndreysProducts
on AndreysProducts.pid = sp2.pid
join products p on sp2.pid = p.pid
join suppliers s2 on s2.fid = sp2.fid
where sp2.price < AndreysProducts.price or AndreysProducts.pid is null

Example

查找以低于我的价格出售的产品

4 个答案: