Question

我这里有一个非常简单的表。我要做的就是返回学生所在年级较高的那一行。我是SQL的初学者，不确定如何解决此问题。

表

Name   Grade   Class
Jim        7   Math
Jim        8   English
Emily      6   Science
Jason     11   Biology
Jason     11   Art
Jason     10   English

预期产量

Name   Grade   Class
Jim        8   English
Emily      6   Science
Jason     11   Biology
Jason     11   Art

Answer 1

您可以使用以下类型查询：

SELECT T1.Name,Grade,Class FROM Table T1
INNER JOIN (SELECT Name,MAX(Grade) MaxGrade FROM Table GROUP BY Name) T2 ON T1.Name=T2.Name AND T1.Grade=T2.MaxGrade

Answer 2

使用相关子查询的一种典型方法：

select t.*
from t
where t.grade = (select max(t2.grade) from t t2 where t2.name = t.name);

SQL Server还有另一个有趣的方法：

select top (1) t.*
from t
order by dense_rank() over (partition by name order by grade desc);

Answer 3

SELECT t.Name
    , t.Grade
    , t.Class
FROM (
    SELECT *
        , Part = RANK() OVER(PARTITION BY Name ORDER BY Grade DESC)
    FROM @t
) t
WHERE t.Part = 1

sql比较列值并返回更大的行

3 个答案: