Need SQl for

Question

I have Table
create table EXAM
STUDENT_ID NUMBER,
MARKS NUMBER
Data for which looks like
STUDENT_ID     MARKS
10     100
20     300
30     200
10     600
20     400
30     300
10     500
20     700
30     900
So if I run this query
SELECT Student_id,marks ,
DENSE_RANK() OVER(PARTITION BY Student_id ORDER BY marks ) AS Rank
FROM exam
I get this
STUDENT_ID     MARKS     RANK
10     100     1
10     500     2
10     600     3
20     300     1
20     400     2
20     700     3
30     200     1
30     300     2
30     900     3
Now My Question is , How I can get the result in (Select statement Note I can write a function or procedure ) to Display Like
Student ID Mark_rank1 Mark_rank2 Mark_rank3
10 100 500 600
20 300 400 700
30 200 300 900
Here in Marks I can just upto 3 Ranks
Thanks In advance

Answer 1

The following should do it:
SELECT student_id
, max(decode(rank, 1, marks, NULL)) mark_rank1
, max(decode(rank, 2, marks, NULL)) mark_rank2
, max(decode(rank, 3, marks, NULL)) mark_rank3
FROM
(SELECT Student_id,marks ,
DENSE_RANK() OVER(PARTITION BY Student_id ORDER BY marks ) AS Rank
FROM exam)
GROUP BY student_id;
Note that if you have same marks, it will be only list once. If you want rank1, rank2 to be same if the first 2 marks same, you have to add some other logic there