Select the Highest value in a Group/Category using SQL Server 2005/2008

In one of my previous posts, I had explained how to SELECT TOP N Rows Per Group/Category

In this query, I will show you how to fetch the highest value in a Group or Category. We will be creating a sample table called Student - StudentId, SubjectId and Marks. We have to find out that in each Subject(group), which Student scored the highest marks.

Sample Data

DECLARE @Student TABLE

(

    StudentId int, SubjectId int, Marks float

)

 

INSERT @Student

SELECT 1,1,8.0 UNION ALL

SELECT 2,1,5.0 UNION ALL

SELECT 3,1,7.0 UNION ALL

SELECT 4,1,9.5 UNION ALL

SELECT 1,2,9.0 UNION ALL

SELECT 2,2,7.0 UNION ALL

SELECT 3,2,4.0 UNION ALL

SELECT 4,2,7.5

Query to fetch Student with highest marks in each Subject

SELECT SubjectId,StudentId,Marks

FROM

(SELECT ROW_NUMBER() OVER(PARTITION BY SubjectId Order by Marks desc) as Topp,* from @Student) Stu

WHERE Stu.Topp =1

Results

SubjectId    StudentId    Marks

1             4            9.5

2             1            9