Classifying Departments in an Org Chart

Problem

A company stores its department hierarchy in `OrgUnits`. Each row has a department id `unit_id` and the id of the department it reports to, `reports_to`. The single top department reports to nobody, so its `reports_to` is NULL. Classify every department into one column `position`:

- `Top` if the department reports to nobody.
- `Middle` if at least one other department reports to it (and it itself reports to someone).
- `Frontline` if no department reports to it.

Return `unit_id` and `position`, ordered by `unit_id` ascending.

Tables

Example rows — the live problem includes the full dataset.

Expected output

Your answer should return 7 rows with the columns unit_id, position.

Starter code (SQL)

SELECT *
FROM OrgUnits;

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