Employees Who Have a Manager — IS NULL in SQL

The problem

Helix Systems' HR team is generating a managed-headcount report for the board, covering only staff who report to a manager.

Write a query to return the name and title of every qualifying 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-level executives have manager_id set to NULL and should be excluded from this report.

Output:

One row per managed employee, 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 NOT NULL

The shape

IS NOT NULL is the complement: keep rows where the value is present. The managed-headcount report excludes top-level executives, and "top-level" is encoded as a NULL manager_id. Filtering to non-null manager links is the exclusion.

Clause by clause

SELECT name, title returns the two columns the board report needs — who, and what role.
FROM employees reads the staff records.
WHERE manager_id IS NOT NULL keeps only rows where the manager link is present. IS NOT NULL returns true for everyone who reports to someone and false for the root, so Sarah Chen drops out and the 60 managed staff stay in.

Why this and not `WHERE manager_id <> NULL`

Both shapes look like they should mean "manager_id is not null," but only IS NOT NULL works. manager_id <> NULL is a comparison: it asks whether the manager link is not equal to NULL. Comparing anything to NULL produces unknown, never true, so the condition fails for every row — the ones with managers and the one without. The query returns zero rows, and the board report comes back empty.

IS NOT NULL is not a comparison. It's a direct test for the presence of a value, and it always returns true or false.

The trap

Any operator that compares to NULL (=, <>, <, >) silently produces an empty or wrong result. No error, no warning. The query runs, the board gets a report, and the headcount is wrong. When the test is for presence or absence of a value, use IS NULL or IS NOT NULL. Never = or <> against NULL.

You practiced testing for the presence of a value with IS NOT NULL. The complement of IS NULL flips the semantic from 'missing' to 'present' and is just as common.

Return the name and title of every qualifying employee

The shape

Clause by clause

Why this and not `WHERE manager_id <> NULL`

The trap

Reading explains SQL. Writing it, over and over with instant feedback, is what makes you fluent.

The shape

Clause by clause

Why this and not WHERE manager_id <> NULL

The trap

Reading explains SQL. Writing it, over and over with instant feedback, is what makes you fluent.

Why this and not `WHERE manager_id <> NULL`