SQL选择组查询

Question

下面是我的表

表格1

+--------+----------+---------+  
| amount | make     | product |  
+--------+----------+---------+  
|    100 | Nokia    | Mobiles |   
|    300 | Samesung | Mobiles |   
|    700 | Micromax | Mobiles |   
|   1000 | Karbonn  | Mobiles |   
|    500 | Lava     | Mobiles |   
|    100 | Floyer   | Gift    |   
|    500 | Arichies | Gift    |   
|    300 | Feeling  | Gift    |   
+--------+----------+---------+  

现在我想为每种产品显示两个最高金额...

所以我想构建单个SQL查询,它给出了如下结果.

+--------+----------+---------+  
| amount | make     | product |  
+--------+----------+---------+  
|   1000 | Karbonn  | Mobiles |   
|    700 | Micromax | Mobiles |   
|    500 | Arichies | Gift    |   
|    300 | Feeling  | Gift    |   
+--------+----------+---------+  

请帮我构建这样的查询..

Answer 1

您可以使用此解决方案根据以下内容检索" group-wise maximum " amount:

SELECT a.*
FROM Table1 a
INNER JOIN Table1 b ON a.product = b.product AND a.amount <= b.amount
GROUP BY a.amount, a.product
HAVING COUNT(*) <= 2

只需将每个产品要检索2的顶部行更改为多个.

如果要检索每个产品的最低两行,只需将<=符号更改INNER JOIN为a即可>=.

你可以在这里找到解决方案:SQL-Fiddle Demo