Who Manages Someone Else?

IT at Kestrel Labs is switching on manager-only screens in the new HR portal, and needs the list of people who should get them. There is no is_manager flag anywhere in the database and no separate table of managers. Being a manager is not something recorded about a person — it is something that shows up because other people point at them.

Each employee row carries a manager_id, the id of the person they report to, left empty for anyone who reports to nobody. So the names IT wants are hidden in that column, written as numbers, on rows belonging to other people entirely. Note also that a manager with three reports is pointed at three times and must still appear once on the list, and that team leads who happen to lead nobody are not managers for this purpose.

employees — one row per person. manager_id is the id of that person's own manager, or NULL if they have none.

The table already exists in the database — there is nothing to create or load.

Task: Write a query returning a single column, name, holding every employee who is pointed at as somebody else's manager. Each such person appears exactly once, however many reports they have. Anyone who leads nobody is absent, including employees whose own manager_id is NULL. Hand the rows back alphabetically by name.

Example output — shape only, on invented names.