Employees with No Manager — IS NULL in SQL

The problem

Helix Systems' HR team is building an organizational chart and needs to identify the top of the reporting hierarchy — the executives who do not report to anyone.

Write a query to return the name and title of every such employee.

Assumptions:

The employees table contains every active and former employee at Helix Systems.
The manager_id column links each employee to their direct manager.
Top-of-hierarchy executives have manager_id set to NULL (no one is above them).

Output:

One row per top-level executive, with columns name and title.

Schema · hr 4 tables

departments

id integer

name text

location text

budget numeric

salaries

id integer

employee_id integer

amount numeric

effective_date date

end_date? date

employees

id integer

name text

email text

department_id integer

manager_id? integer

hire_date date

title text

is_active boolean

job_history

id integer

employee_id integer

title text

department_id integer

start_date date

end_date? date

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Worked solution Try it yourself first

Solution query

SELECT
  name,
  title
FROM
  employees
WHERE
  manager_id IS NULL

The shape

The top of a reporting hierarchy is encoded as the absence of a manager. Sarah Chen, the CEO, has no one above her, so her manager_id is NULL. IS NULL is what surfaces that row.

Clause by clause

SELECT name, title returns the two pieces of information the org chart needs at the root level — who, and what role. manager_id itself stays out of the output; it's NULL for every row in the result.
FROM employees reads the staff records. The prompt's assumption that this table contains everyone (active and former) is what guarantees the root is reachable from this single table.
WHERE manager_id IS NULL keeps only the row whose manager link is absent. In a hierarchy with a single CEO, that returns one row.

The trap

WHERE manager_id = NULL returns zero rows no matter how many top-level executives exist. Comparing to NULL with = produces unknown, never true, and WHERE drops rows whose condition isn't clearly true. The query runs, the org chart comes back empty at the top, and the structural assumption ("someone has to be at the root") quietly fails. IS NULL is the only test that asks the right question.

You practiced using IS NULL to find the top of a hierarchy. Self-referential tables (employees who manage other employees) almost always use NULL to mark the root.

Return the name and title of every such employee

The shape

Clause by clause

The trap

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