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Earning More Than the Boss (Self Join)
A comp-equity audit wants to surface every case where an employee earns more than their direct manager — a structural red flag worth a manual review (sometimes it's the right thing, e.g. a specialist IC under a generalist manager; sometimes it's a pay-band mistake).
Using a self join, show emp_name, emp_salary, manager_name, manager_salary, and diff (emp_salary - manager_salary). Order by diff descending.
This is a classic self-join interview question: it tests whether you can comfortably alias the same table twice and remember which alias means what.
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Schema
employees
| emp_id | name | department | position | salary | hire_date | manager_id | performance_rating |
|---|---|---|---|---|---|---|---|
| 1 | Alice Johnson | Engineering | Senior Developer | 95000 | 2019-03-15 | 5 | 4.5 |
| 2 | Bob Smith | Engineering | Developer | 75000 | 2020-06-01 | 1 | 3.8 |
| 3 | Carol Williams | Marketing | Marketing Manager | 85000 | 2018-09-20 | NULL | 4.2 |
Expected output: Alice | 95000 | Bob | 80000 | 15000
Hint
e.salary - m.salary in SELECT.Concepts
SELECT JOIN Self Join WHERE
Practise the topic: SQL practice questions · JOIN practice
Read the concept: The anti-join, three ways
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