Puoi utilizzare una sottoquery correlata per trovare il disp_order più recente per il livello precedente:
Impostazione dello schema Oracle 11g R2 :
CREATE TABLE tbl_pattern ( order_no, code, disp_order, lvl, description ) AS
SELECT 'RM001-01', 1, 0, 1, 'HK140904-1A' FROM DUAL UNION ALL
SELECT 'RM001-01', 1, 1, 2, 'HK140904-1B' FROM DUAL UNION ALL
SELECT 'RM001-01', 1, 2, 3, 'HK140904-1B' FROM DUAL UNION ALL
SELECT 'RM001-01', 1, 3, 4, 'HK140904-1C' FROM DUAL UNION ALL
SELECT 'RM001-01', 1, 4, 5, 'HK140904-1D' FROM DUAL UNION ALL
SELECT 'RM001-01', 1, 5, 2, 'HK140904-1E' FROM DUAL UNION ALL
SELECT 'RM001-01', 1, 6, 3, 'HK140904-1E' FROM DUAL UNION ALL
SELECT 'RM001-01', 1, 7, 3, 'HK140904-1X' FROM DUAL UNION ALL
SELECT 'RM001-01', 1, 8, 4, 'HK140904-1E' FROM DUAL UNION ALL
SELECT 'RM001-01', 1, 9, 5, 'HK140904-1E' FROM DUAL;
Query 1 :
SELECT t.*,
( SELECT MAX( disp_order )
FROM tbl_pattern p
WHERE p.order_no = t.order_no
AND p.code = t.code
AND p.lvl = t.lvl - 1
AND p.disp_order < t.disp_order ) AS parent
FROM tbl_pattern t
| ORDER_NO | CODE | DISP_ORDER | LVL | DESCRIPTION | PARENT |
|----------|------|------------|-----|-------------|--------|
| RM001-01 | 1 | 0 | 1 | HK140904-1A | (null) |
| RM001-01 | 1 | 1 | 2 | HK140904-1B | 0 |
| RM001-01 | 1 | 2 | 3 | HK140904-1B | 1 |
| RM001-01 | 1 | 3 | 4 | HK140904-1C | 2 |
| RM001-01 | 1 | 4 | 5 | HK140904-1D | 3 |
| RM001-01 | 1 | 5 | 2 | HK140904-1E | 0 |
| RM001-01 | 1 | 6 | 3 | HK140904-1E | 5 |
| RM001-01 | 1 | 7 | 3 | HK140904-1X | 5 |
| RM001-01 | 1 | 8 | 4 | HK140904-1E | 7 |
| RM001-01 | 1 | 9 | 5 | HK140904-1E | 8 |
