Three-table INNER JOIN
- SQL course
- Intermediate
- Lesson 3/115
- 4 min
Chain JOINs across three tables.
Three-table INNER JOIN
Multiple INNER JOINs chain together. Each JOIN connects the next table with its own ON condition.
SELECT * FROM orders o
INNER JOIN customers c ON o.customer_id = c.id
INNER JOIN products p ON o.product_id = p.id;This query joins orders, customers and products.
All columns are selected from orders o. customers c is joined on o.customer_id = c.id, keeping only matching rows. products p is joined on o.product_id = p.id, keeping only matching rows.
Three-table INNER JOIN — details
Each JOIN takes its own ON. Order affects readability, not the result.
For example, joining orders, customers and products shows the customer name and product name side by side on every order row.
Practice Three-table INNER JOIN
Chain orders, customers and products with INNER JOIN.
Starter code
-- join three tables
SELECT * FROM orders o
INNER JOIN customers c ON o.customer_id = c.idSample solution
SELECT * FROM orders o
INNER JOIN customers c ON o.customer_id = c.id
INNER JOIN products p ON o.product_id = p.id;Expected output
order_id customer product 1 Ayşe Kalem 2 Mehmet Defter
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Three-table INNER JOIN: match the terms
| Term | Meaning |
|---|---|
JOIN |
combine |
ON |
condition |
AS |
alias |
WHERE |
filter |
2 Add the third table
SELECT * FROM orders o
INNER JOIN customers c ON o.customer_id = c.id
____ products p ON o.product_id = p.id;SELECT * FROM orders o
INNER JOIN customers c ON o.customer_id = c.id
INNER JOIN products p ON o.product_id = p.id;Explanation: INNER JOIN is the right answer.
3 How many ON clauses for three tables?
- Three
- Two Correct answer
- One
- None
Explanation: Two JOINs need two ON conditions.