Question

Good Morning All.

I have a table structure (I am using SQL SERVER 2000)

CourseID StudentName TermPaperID

101         Jon            1   
101         Jon            2
101         Jon            3
101         David          1   
101         David          2
102         David          5 
102         David          6 
102         George         5  

I would like to list out CourseID,StudentName,Maximum registration per Course.

I tried the following Query

select 
CourseId,
StudentName,
max(x.numberofregistration) as max_registration
from
(
   select 
           CourseID,
           StudentName,
           count(CourseID) as numberofregistration 
    from 
    dbo.Students 
            group by CourseId,StudentName
 )x
 group by CourseId,StudentName

but it did no give the expected result.

The expected result is
I have a table structure

CourseID StudentName max_registration

101         Jon            3   
102         David          2

How to achieve the expected result? Thanks in advance.

Answer 1

Here’s a really, really ugly way. I think I’d rather pony up the upgrade fee than write too many of these. Hopefully someone else will come up with something cleaner.

CREATE TABLE #x(CourseID INT, StudentName VARCHAR(32), TermPaperID INT);

INSERT #x SELECT 101,'Jon   ',1;   
INSERT #x SELECT 101,'Jon   ',2;
INSERT #x SELECT 101,'Jon   ',3;
INSERT #x SELECT 101,'David ',1;   
INSERT #x SELECT 101,'David ',2;
INSERT #x SELECT 102,'David ',5; 
INSERT #x SELECT 102,'David ',6; 
INSERT #x SELECT 102,'George',5;

SELECT b.CourseID, b.StudentName, max_registration = COUNT(*)
FROM #x AS b
INNER JOIN (
  SELECT CourseID, c = MAX(c)
  FROM
  (
    SELECT CourseID, StudentName, c = COUNT(CourseID) 
    FROM #x GROUP BY CourseID, StudentName
  ) AS x GROUP BY CourseID
) AS s
ON b.CourseID = s.CourseID
GROUP BY b.CourseID, b.StudentName
HAVING COUNT(*) = MAX(s.c)
ORDER BY b.CourseID;