students enrolled in the most classes (Select Stat

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students enrolled in the most classes (Select Stat

Author

Topic

Prosercunus
Starting Member

22 Posts

Posted - 2012-10-11 : 23:04:27

Using select statements find the name(s) and sid(s) of the student(s) enrolled in the most classes.

So far I have...

select Student.sid, sname, Major.dname from Student, Major

I now need to find those students that are enrolled in the most classes. I can see all of the classes they are in, just unsure what statement to make it show it only shows the students enrolled in the most amount of classes or (dname).

Here are the two tables.

Major(dname,sid)
Student(sid,sname,sex,age,year,qpa)

sql-programmers
Posting Yak Master

190 Posts

Posted - 2012-10-12 : 00:33:01

Hi,

Try this,

DECLARE @Major AS TABLE (dname VARCHAR(50),SID INT )
DECLARE @Student AS TABLE (SID INT IDENTITY,sname VARCHAR(50),sex CHAR(1),age INT,[year] INT)

INSERT INTO @Student (sname, sex, age, [year]) VALUES ('A', 'M', 12, 1999)
INSERT INTO @Student (sname, sex, age, [year]) VALUES ('B', 'M', 13, 2000)
INSERT INTO @Student (sname, sex, age, [year]) VALUES ('C', 'F', 13, 2000)
INSERT INTO @Student (sname, sex, age, [year]) VALUES ('D', 'M', 15, 1999)
INSERT INTO @Student (sname, sex, age, [year]) VALUES ('E', 'F', 16, 1999)

INSERT INTO @Major ( dname, SID )VALUES ( 'D 1', 1)
INSERT INTO @Major ( dname, SID )VALUES ( 'D 2', 1)
INSERT INTO @Major ( dname, SID )VALUES ( 'D 3', 1)
INSERT INTO @Major ( dname, SID )VALUES ( 'D 1', 2)
INSERT INTO @Major ( dname, SID )VALUES ( 'D 2', 2)
INSERT INTO @Major ( dname, SID )VALUES ( 'D 1', 3)
INSERT INTO @Major ( dname, SID )VALUES ( 'D 2', 4)
INSERT INTO @Major ( dname, SID )VALUES ( 'D 3', 5)

SELECT M.SID, COUNT(*) FROM @Student S
INNER JOIN @Major M ON s.SID = m.SID
GROUP BY M.SID HAVING COUNT(*) > 1

SELECT S.SID, S.sname, M.dname FROM @Student S
INNER JOIN (
SELECT M.SID, COUNT(*) AS Cnt FROM @Student S
INNER JOIN @Major M ON s.SID = m.SID
GROUP BY M.SID HAVING COUNT(*) > 1
) AS M1 ON m1.SID = s.sid
INNER JOIN @Major M ON M1.SID = m.SID

SQL Server Programmers and Consultants
http://www.sql-programmers.com/

bandi
Master Smack Fu Yak Hacker

2242 Posts

Posted - 2012-10-12 : 00:36:48

Hi,

Alternate Solution is:

;with cte
as
(SELECT sid, dname, count(dname) over(Partition by sid) noOfDepts from Major)
select S.*, dname, noOfDepts
FROM student s
JOIN cte m ON s.sid = m.sid
WHERE noOfDepts = (SELECT MAX(noOfDepts) FROM cte)

--
Chandu

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