Oracle 11g Release 2

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.

CREATE TABLE test_data( id, object, bc003, track_change ) AS
SELECT 121, 12,  1, 15   FROM DUAL UNION ALL
SELECT 121, 13,  1, NULL FROM DUAL UNION ALL
SELECT 121, 14,  1, NULL FROM DUAL UNION ALL
SELECT 121, 15,  1, NULL FROM DUAL UNION ALL
SELECT 121, 16,  1, NULL FROM DUAL UNION ALL
SELECT 121, 12, 18, 22   FROM DUAL UNION ALL
SELECT 121, 13, 18, NULL FROM DUAL UNION ALL
SELECT 121, 14, 18, NULL FROM DUAL UNION ALL
SELECT 121, 15, 18, NULL FROM DUAL UNION ALL
SELECT 121, 16, 18, NULL FROM DUAL
10 rows affected

SELECT t.*,
       MIN( track_change ) OVER ( PARTITION BY id, bc003 ) AS track_change_new
FROM   test_data t


ID
OBJECT
BC003
TRACK_CHANGE
TRACK_CHANGE_NEW


121
12
1
15
15

121
13
1
null
15

121
14
1
null
15

121
15
1
null
15

121
16
1
null
15

121
12
18
22
22

121
13
18
null
22

121
14
18
null
22

121
15
18
null
22

121
16
18
null
22


SELECT t.*,
       COALESCE(
         track_change,
         LAG( track_change ) IGNORE NULLS OVER (
           PARTITION BY id, bc003
           ORDER BY object
         )
       ) AS track_change_new
FROM   test_data t


ID
OBJECT
BC003
TRACK_CHANGE
TRACK_CHANGE_NEW


121
12
1
15
15

121
13
1
null
15

121
14
1
null
15

121
15
1
null
15

121
16
1
null
15

121
12
18
22
22

121
13
18
null
22

121
14
18
null
22

121
15
18
null
22

121
16
18
null
22

ID	OBJECT	BC003	TRACK_CHANGE	TRACK_CHANGE_NEW
121	12	1	15	15
121	13	1	null	15
121	14	1	null	15
121	15	1	null	15
121	16	1	null	15
121	12	18	22	22
121	13	18	null	22
121	14	18	null	22
121	15	18	null	22
121	16	18	null	22