SQL Fundamentals · Joins · Lesson 13 of 17
INNER JOIN
Concept
INNER JOIN
INNER JOIN returns only the rows that have a match in both tables being joined.
By the end of this lesson
- Explain the core idea behind INNER JOIN.
- Predict output before running a change.
- Test one realistic and one unusual input.
- Use the result to make the next decision.
How to study this page
- 1. Read one concept.
- 2. Change the example.
- 3. Run, compare, and explain.
- 4. Complete the challenge below.
ExampleRunnable
SELECT students.name, courses.title
FROM students
INNER JOIN enrollments ON students.id = enrollments.student_id
INNER JOIN courses ON enrollments.course_id = courses.id;Self-check before continuing
Without looking at the example, describe what changes when you modify one input in INNER JOIN. Then reopen the editor and prove your explanation with a small test.
You are ready to continue when you can predict, test, and explain the result.
Your turn
Explain what would happen to a student with no enrollments in an INNER JOIN.
Loading editor…
Console