T-SQL 获取与 group by 中的聚合匹配的列

Question

我做了一个非常简单的示例 http://sqlfiddle.com/#!6/d2cc0/4

我有一个 table "People" 有名字、年龄和体重。我想检索每个年龄段最轻的人的名字。

我按年龄对人进行分组，这样我就可以检索每个不同年龄段最轻的人的体重，但是如何检索与 min() 聚合匹配的姓名？

Answer 1

以下查询将 return 姓名、年龄和最小体重：

SELECT P.* from People P JOIN (SELECT
  age,
  min(weight) as lightest
FROM
  People 
GROUP BY age) T on p.age = T.age and p.weight = T.lightest

输出：

| name | age | weight |
|------|-----|--------|
|    A |  20 |     60 |
|    C |  25 |     70 |

Answer 2

使用分区：

Select * from (
    Select *
    , min(weight) over (partition by age) as MinWeight 
    from People) a
where Weight = MinWeight

或：

Select * from people a
where weight = (select min(weight) from people b where a.age = b.age)

请注意，如果有关系，两者将 return 每个年龄段的人都不止一个。

T-SQL get column that matches aggregate in group by