Group by multiple columns problem

Question

I am having some problems with my query. For example:
SELECT STUDENTNUMBER FROM REGISTRATION
WHERE TERM='A1' AND YEAR=2008
GROUP BY STUDENTNUMBER
HAVING COUNT( COURSECODE) = 1;
which returns:
STUDENTNUMBER
123456
789012
6 rows selected
Which is ok, but the problem is i want to list out not only studentnumber but also the coursecode,year and the term of students. But if i do this:
SELECT STUDENTNUMBER,COURSECODE,YEAR,TERM,
FROM REGISTRATION WHERE TERM='A1'AND YEAR=2008
GROUP BY (STUDENTNUMBER,COURSECODE,YEAR,TERM)
HAVING COUNT( COURSECODE) = 1;
i got 50+ records in which most of them are duplicates!. To put it shortly i want the 6 records but with the coursecode,year,studentnumber and term listed. is there a workaround for this?

Answer 1

Thanks everyone for your suggestion!
I end up using Arun's query but modify it slightly to this:
SELECT STUDENTNUMBER,COURSECODE,YEAR,TERM
FROM REGISTRATION WHERE STUDENTNUM IN(
SELECT STUDENTNUMBER FROM REGISTRATION
WHERE TERM='A1' AND YEAR=2008
GROUP BY STUDENTNUMBER
HAVING COUNT(COURSECODE) = 1) AND TERM='A1' AND YEAR=2008;
Using the multiple set functions would also yields the same result.Anyway i would post the create table statements and insert statements for everyone's references.
CREATE TABLE REGISTRATION(
     CourseCode     VARCHAR(15)     NOT NULL     ,
     Year          NUMBER(4)     NOT NULL     ,
     Term          VARCHAR(5)     NOT NULL     ,
     StudentNumber     NUMBER(12)     NOT NULL     ,
     Lecturer          NUMBER(12)     NOT NULL     ,
     Grade          NUMBER(5,2)               ,
     CONSTRAINT REGISTRATION_PKEY PRIMARY KEY(CourseCode, Year, Term, StudentNumber, Lecturer),
     CONSTRAINT REGISTRATION_FKEY1 FOREIGN KEY(CourseCode) REFERENCES COURSE(CourseCode),
     CONSTRAINT REGISTRATION_FKEY2 FOREIGN KEY(StudentNum) REFERENCES STUDENT(StudentNumber),
     CONSTRAINT REGISTRATION_FKEY3 FOREIGN KEY(Lecturer) REFERENCES ACADSTAFF(StaffNum)
Insert statements:
INSERT INTO REGISTRATION VALUES('CSE235',2008,'A1',1292601,2001,null);
INSERT INTO REGISTRATION VALUES('CSE235',2008,'A2',8290012,2001,null);
INSERT INTO REGISTRATION VALUES('CSE235',2008,'A2',7246935,2002,null);
I want to list the student number, coursecode, year and term of students who registers for only one course in term "A1" in 2008.The result:
STUDENTNUM COURSECODE YEAR TERM
3000911 CSE101 2008 A1
3335010 CSE101 2008 A1
3011724 CSE101 2008 A1
8754117 CSE101 2008 A1
1032858 CSE101 2008 A1
3292880 CSE101 2008 A1
6 rows selected.
Edited by: user12231119 on Nov 16, 2009 9:19 PM