SQL:查找每组的最大记录 [英] SQL: Find the max record per group

问题描述

<块引用>

可能的重复:
检索每组中的最后一条记录

我有一张表，其中包含三个字段和数据.

<前>名称 , 顶部 , 总计猫 , 1 , 10狗 , 2 , 7猫 , 3 , 20马 , 4 , 4猫 , 5 , 10狗 , 6 , 9

我想为每个Name选择Total值最高的记录，所以我的结果应该是这样的:

<前>名称 , 顶部 , 总计猫 , 3 , 20马 , 4 , 4狗 , 6 , 9

我尝试按名称顺序按总数分组，但它给出了按结果分组的最高记录.谁能指导我好吗?

解决方案

select名称、顶部、总计从有的在哪里Total = (select max(Total) from sometable i where i.Name = sometable.Name)

或

选择名称、顶部、总计从有的内部联接 (选择 max(Total) Total, Name从某个表按名称分组) 作为 max.Name = sometable.Name 和 max.Total = sometable.Total 上的最大值

Possible Duplicate:
Retrieving the last record in each group

I have one table, which has three fields and data.

Name  , Top , Total
cat   ,   1 ,    10
dog   ,   2 ,     7
cat   ,   3 ,    20
horse ,   4 ,     4
cat   ,   5 ,    10
dog   ,   6 ,     9

I want to select the record which has highest value of Total for each Name, so my result should be like this:

Name  , Top , Total
cat   ,   3 ,    20
horse ,   4 ,     4
Dog   ,   6 ,     9

I tried group by name order by total, but it give top most record of group by result. Can anyone guide me, please?

解决方案

select
  Name, Top, Total
from
  sometable
where
  Total = (select max(Total) from sometable i where i.Name = sometable.Name)

or

select
  Name, Top, Total
from
  sometable
  inner join (
    select max(Total) Total, Name
    from sometable
    group by Name
  ) as max on max.Name = sometable.Name and max.Total = sometable.Total

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