Sort values in an associative array pl/sql - sorting

Question

If ID is even I must sort the values that correspond to that ID DESC , if the ID is odd I must sort the values ASC. This is the table called Grades.
ID|COL1|COL2|COL3|COL4|COL5|COL6|COL7|
1 | 6 | 3 | 8 | 4 | 7 | 8 | 4 |
2 | 5 | 7 | 9 | 2 | 1 | 7 | 8 |
3 | 2 | 7 | 4 | 8 | 1 | 5 | 9 |
4 | 8 | 4 | 7 | 9 | 4 | 1 | 4 |
5 | 7 | 5 | 2 | 5 | 2 | 6 | 4 |
The result must be this:
ID|COL1|COL2|COL3|COL4|COL5|COL6|COL7|
1 | 3 | 4 | 4 | 6 | 7 | 8 | 8 |
2 | 9 | 8 | 7 | 7 | 5 | 2 | 1 |
3 | 1 | 2 | 4 | 5 | 7 | 8 | 9 |
4 | 9 | 8 | 7 | 4 | 4 | 4 | 1 |
5 | 2 | 2 | 4 | 5 | 5 | 6 | 7 |
As you can see ID=1->odd number so the values must be sorted ASC
This is the code so far:
declare
type grades_array is table of grades%rowtype index by pls_integer;
grades_a grades_array;
cnt number;
begin
Select count(id) into cnt from grades;
For i in 1..cnt loop
--I used an associative array
Select * into grades_a(i) from grades where grades.id=i;
end loop;
For i in grades_a.FIRST..grades_a.LAST loop
if (mod(grades_a(i).id,2)=1)then .......
--I don't know how to sort the specific rows, in this case ASC
--dbms_output.put_line(grades_a(i).col1);
end if;
end loop;
--Also it is specified in the exercise that the table can change, e.g add more columns
end;

Answer 1

I would simply use PIVOT/UNPIVOT for this.
First UNPIVOT the table and assign a rank to each column value in ascending/descending order.
SQL Fiddle
Query 1:
SELECT id,
colval,
ROW_NUMBER () OVER (
PARTITION BY id
ORDER BY CASE MOD (id, 2) WHEN 1 THEN colval END,
CASE MOD (id, 2) WHEN 0 THEN colval END DESC) r
FROM x UNPIVOT (colval FOR colname
IN (col1 AS 'col1', col2 AS 'col2', col3 AS 'col3', col4 AS 'col4',
col5 AS 'col5', col6 AS 'col6', col7 AS 'col7')
)
Results:
| ID | COLVAL | R |
|----|--------|---|
| 1 | 3 | 1 |
| 1 | 4 | 2 |
| 1 | 4 | 3 |
| 1 | 6 | 4 |
| 1 | 7 | 5 |
| 1 | 8 | 6 |
| 1 | 8 | 7 |
| 2 | 9 | 1 |
| 2 | 8 | 2 |
| 2 | 7 | 3 |
| 2 | 7 | 4 |
| 2 | 5 | 5 |
| 2 | 2 | 6 |
| 2 | 1 | 7 |
| 3 | 1 | 1 |
| 3 | 2 | 2 |
| 3 | 4 | 3 |
| 3 | 5 | 4 |
| 3 | 7 | 5 |
| 3 | 8 | 6 |
| 3 | 9 | 7 |
| 4 | 9 | 1 |
| 4 | 8 | 2 |
| 4 | 7 | 3 |
| 4 | 4 | 4 |
| 4 | 4 | 5 |
| 4 | 4 | 6 |
| 4 | 1 | 7 |
| 5 | 2 | 1 |
| 5 | 2 | 2 |
| 5 | 4 | 3 |
| 5 | 5 | 4 |
| 5 | 5 | 5 |
| 5 | 6 | 6 |
| 5 | 7 | 7 |
Then PIVOT the result based on the rank.
Query 2:
WITH pivoted AS (
SELECT id,
colval,
ROW_NUMBER () OVER (
PARTITION BY id
ORDER BY CASE MOD (id, 2) WHEN 1 THEN colval END,
CASE MOD (id, 2) WHEN 0 THEN colval END DESC) r
FROM x UNPIVOT (colval FOR colname
IN (col1 AS 'col1', col2 AS 'col2', col3 AS 'col3', col4 AS 'col4',
col5 AS 'col5', col6 AS 'col6', col7 AS 'col7')
)
)
SELECT * FROM pivoted
PIVOT (MAX (colval)
FOR r
IN (1 AS col1, 2 AS col2, 3 AS col3, 4 AS col4,
5 AS col5, 6 AS col6, 7 AS col7))
Results:
| ID | COL1 | COL2 | COL3 | COL4 | COL5 | COL6 | COL7 |
|----|------|------|------|------|------|------|------|
| 1 | 3 | 4 | 4 | 6 | 7 | 8 | 8 |
| 2 | 9 | 8 | 7 | 7 | 5 | 2 | 1 |
| 3 | 1 | 2 | 4 | 5 | 7 | 8 | 9 |
| 4 | 9 | 8 | 7 | 4 | 4 | 4 | 1 |
| 5 | 2 | 2 | 4 | 5 | 5 | 6 | 7 |