Data migration-compact and move --

Data migration-compact and move --

The current requirement is that the following result sets become compact:

COL1 COL2 COL3
------------------------------

1
2
3
4
5
6
7
8
9
10
11
12

COL1 COL2 COL3
------------------------------
1 7 11
2 8 12
3 9
4 10
5
6

Drop table test;
Create table test (col1 number, col2 number, col3 number );
Insert into test values (1, null, null );
Insert into test values (2, null, null );
Insert into test values (3, null, null );
Insert into test values (4, null, null );
Insert into test values (5, null, null );
Insert into test values (6, null, null );
Insert into test values (null, 7, null );
Insert into test values (null, 8, null );
Insert into test values (null, 9, null );
Insert into test values (null, 10, null );
Insert into test values (null, null, 11 );
Insert into test values (null, null, 12 );
Commit;

SQL> select * from test;
COL1 COL2 COL3
------------------------------
1
2
3
4
5
6
7
8
9
10
11
12

The idea is to find out each column and then perform a left join:
With t1 as (select rownum rn, col1 from test where col1 is not null ),
T2 as (select rownum rn, col2 from test where col2 is not null ),
T3 as (select rownum rn, col3 from test where col3 is not null)
Select col1, col2, col3 from t1, t2, t3 where t1.rn = t2.rn (+) and t2.rn = t3.rn (+)
Order by t1.rn;

COL1 COL2 COL3
------------------------------
1 7 11
2 8 12
3 9
4 10
5
6