LEFT JOIN Missing Matches

How can we find employees who have no department?

Advanced⏱ 3 Minutes⭐ 1000 XP

🤔 THE QUESTION

How can we find employees who have no department?

💡 WHAT IS IT?

Filtering for IS NULL on the right table's primary key after a LEFT JOIN isolates unmatched records.

🎯 WHAT IS IT USED FOR?

Orphan record detection, unassigned employee auditing, missing reference cleanup.

💻 EXAMPLE

SELECT e.name
FROM employees e
LEFT JOIN departments d
ON e.department_id = d.department_id
WHERE d.department_id IS NULL;

Practice typing production-grade SQL code for LEFT JOIN Missing Matches.