Practice / joins
An HR tool stores an org chart in one employees table: each person has an id, a name, and an optional manager_id pointing at another employee's id.
employees
Your task: return employee and manager — each person's name and their manager's name. People with no manager can be dropped.
Assign your answer DataFrame to result. Row order doesn't matter.
employeesinput DataFrame| column | type |
|---|---|
| id | long |
| name | string |
| manager_id | long |
| id | name | manager_id |
|---|---|---|
| 1 | Rae | null |
| 2 | Sol | 1 |
| 3 | Uma | 1 |
| 4 | Ivo | 2 |
employeemanager· 3 rowsAlias the table twice and join it to itself: e = employees.alias("e"),
m = employees.alias("m"), then join e.manager_id == m.id. Select
e.name as the employee and m.name as the manager.
This problem builds on Joins (~8 min). Pop it open in a new tab if you want a quick recap.