Question

鉴于此表，我想为每个不同的URL检索具有最大计数的行。对于此表，输出应为：'dell.html'3，'lenovo.html'4，'toshiba.html'5

+----------------+-------+
| url            | count |
+----------------+-------+
| 'dell.html'    |     1 |
| 'dell.html'    |     2 |
| 'dell.html'    |     3 |
| 'lenovo.html'  |     1 |
| 'lenovo.html'  |     2 |
| 'lenovo.html'  |     3 |
| 'lenovo.html'  |     4 |
| 'toshiba.html' |     1 |
| 'toshiba.html' |     2 |
| 'toshiba.html' |     3 |
| 'toshiba.html' |     4 |
| 'toshiba.html' |     5 |
+----------------+-------+

要执行此操作，我需要编写什么SQL查询？

Answer 1

尝试使用此查询：

select url, max(count) as count
from table_name
group by url;

Answer 2

使用聚合函数

  select max(count) ,url from table_name group by url

从您的评论看来，您需要相关的子查询

select t1.* from table_name t1
 where t1.count = (select max(count) from table_name t2 where t2.url=t1.url
                 )

如果您的sqllite版本支持row_number 那么您可以编写如下查询

select * from 
(
select *,row_number() over(partition by url  order by count desc) rn
  from table_name
) a where a.rn=1

如何选择具有最大值的行？

2 个答案: