使用相同的项目名称选择行和显示最低价格

Question

我们已经制定了一个两个表：

Products 
ID | Item | Supplier 
1 | Harry Potter | Warner 
2 | Harry Potter | Warner 
3 | Game of Thrones | HBO 
4 | The Simpsons | Warner 
5 | The Simpsons | Warner 

和

Prices 
ID | Price 
1 | 10.99 
2 | 20.00 
3 | 20.00 
4 | 10.00 
5 | 12.00 

我试图让价格最低的ID有两个项目名称和供应商名称相同的项目。

我能在那里有重复的行：

SELECT 
Products.ID,Products.Item,Products.Supplier,Prices.price 
FROM 
Products 
LEFT JOIN Prices ON Prices.ID = Products.ID 
WHERE Products.ID IN (
SELECT ID FROM Products WHERE Supplier="Warner" GROUP BY Item HAVING count(*) > 1 
) 

我怎么能那么修改这个显示价格最低的重复的项目名称的只有Products.ID？

我尝试过ORDER BY，但是这会为我引发一个错误。

结果应该是：

ID | Item | Supplier | Price 
1 | Harry Potter | Warner | 10.99 
4 | The Simpsons | Warner | 10.00 

感谢，

里克

Answer 1

第一的所有表的实现必须改善，如果您有ID为Products表中数据主键将如下（你需要一个主键）。

Products 
ID | Item | Supplier 
1 | Harry Potter | Warner 
2 | Game of Thrones | HBO 

Prices 
ID | Price 
1 | 10.99 
1 | 20.00 
2 | 20 

为了选择最低价格的商品，使用min函数

现在

SELECT 
Products.ID,Products.Item,Products.Supplier, MIN(Prices.price) 
FROM 
Products 
LEFT JOIN Prices ON Prices.ID = Products.ID; 

Answer 2

/* Oracle syntax 
with Products as 
( 
select 1 id, 'Harry Potter' item, 'Warner' supplier from dual union all 
select 2 id, 'Harry Potter' item, 'Warner' supplier from dual union all 
select 3, 'Game of Thrones', 'HBO' from dual union all 
select 4, 'the simpsons', 'Warner' from dual union all 
select 5, 'the simpsons', 'Warner' from dual 
), 
Prices as 
( 
select 1 id, 10.99 price from dual union all 
select 2, 20.00 from dual union all 
select 3, 20.00 from dual union all 
select 4, 10.00 from dual union all 
select 5, 12.00 from dual) 
*/ 

select distinct p.id from Products p join Prices c 
on (p.id = c.id) 
where (p.item, p.supplier, c.price) in 
(select item, supplier, min(price) from Products p join Prices c on (p.id = c.id) group by item, supplier having count(item) > 1); 

（若有几个产品具有相同的项目价值和价格此查询会同时显示产品）