How does one unpivot from a pivoted table such as this?
Table A:
+----+------------+--------+--------+--------+
| Id | Level0 | Level1 | Level2 | Level3 |
+----+------------+--------+--------+--------+
| 0 | TMI | | | |
+----+------------+--------+--------+--------+
| 1 | TMI | A | | |
+----+------------+--------+--------+--------+
| 2 | TMI | A | B | |
+----+------------+--------+--------+--------+
| 3 | TMI | A | B | C |
+----+------------+--------+--------+--------+
| 4 | TMI | A | B | D |
+----+------------+--------+--------+--------+
Back to self referencing table like this:
Table B:
+----+-----------+----------+--------+
| Id | LevelName | ParentId | Level |
+----+-----------+----------+--------+
| 0 | TMI | | Level0 |
+----+-----------+----------+--------+
| 1 | A | 0 | Level1 |
+----+-----------+----------+--------+
| 2 | B | 1 | Level2 |
+----+-----------+----------+--------+
| 3 | C | 2 | Level3 |
+----+-----------+----------+--------+
| 4 | D | 2 | Level3 |
+----+-----------+----------+--------+
I can go from Table B
to Table A
, but how to go from Table A
to Table B
?