+------+-------+---------+
| enum | name  | manager |
+------+-------+---------+
|   10 | John  |    NULL |
|   20 | Peter |      10 |
|   30 | Mary  |      10 |
|   40 | Mike  |      20 |
|   50 | Kate  |      20 |
|   60 | Greg  |      50 |
|   70 | Phil  |      50 |
+------+-------+---------+