By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.
8 rows affected
| UID | A1 | A2 | A3 | A4 | R1ID | R2ID |
|---|---|---|---|---|---|---|
| 7 | null | null | C3 | null | 1 | 1 |
| 8 | null | null | C3 | d7 | 1 | 2 |
| 1 | A1 | B1 | C1 | null | 2 | 1 |
| 2 | A1 | B1 | C1 | D1 | 2 | 2 |
| 4 | A1 | B1 | C1 | D2 | 2 | 3 |
| 3 | A2 | B2 | C2 | D1 | 3 | 1 |
| 5 | A2 | B2 | C2 | D4 | 3 | 2 |
| 6 | A2 | B2 | C2 | D6 | 3 | 3 |