INNER JOIN

INNER JOIN returns only rows where the join condition matches in BOTH tables. Rows that don't match are excluded from the result. This is the most common join type and the default when you write just JOIN.

15 min•By Priygop Team•Updated 2026

INNER JOIN Key Points

Returns only MATCHING rows from both tables
Unmatched rows are dropped — if user has no orders, they won't appear
Written as JOIN or INNER JOIN (identical)
Multiple INNER JOINs chain naturally for multi-table queries
Most commonly used in production queries

INNER JOIN Examples on ecommerce_db

-- Join users with their orders
SELECT
  u.name AS customer,
  u.email,
  o.id AS order_id,
  o.total_amount,
  o.status
FROM users u
INNER JOIN orders o ON u.id = o.user_id;

-- Result (Bob Lee not shown — no orders):
-- customer    | email           | order_id | total_amount | status
-- John Doe    | john@...        | 1        | 999.99       | delivered
-- John Doe    | john@...        | 3        | 89.99        | shipped
-- Alice Smith | alice@...       | 2        | 599.99       | pending

-- Join orders with payments
SELECT
  o.id AS order_id,
  o.status,
  p.amount AS paid,
  p.payment_method
FROM orders o
INNER JOIN payments p ON o.id = p.order_id;
-- Only orders WITH payments appear

-- Three-table INNER JOIN
SELECT
  u.name, o.id AS order_id, p.amount, p.payment_method
FROM users u
JOIN orders o ON u.id = o.user_id
JOIN payments p ON o.id = p.order_id;

Quick Quiz

Tip

Practice INNER JOIN in small, isolated examples before integrating into larger projects. Breaking concepts into small experiments builds genuine understanding faster than reading alone.

Diagram

Loading diagram…

Relationships define how tables connect through foreign keys

Common Mistake

Warning

A common mistake with INNER JOIN is skipping edge case testing — empty inputs, null values, and unexpected data types. Always validate boundary conditions to write robust, production-ready sql code.

Practice Task

Note

Practice Task — (1) Write a working example of INNER JOIN from scratch without looking at notes. (2) Modify it to handle an edge case (empty input, null value, or error state). (3) Share your solution in the Priygop community for feedback.

Key Takeaways

INNER JOIN returns only rows where the join condition matches in BOTH tables.
Returns only MATCHING rows from both tables
Unmatched rows are dropped — if user has no orders, they won't appear
Written as JOIN or INNER JOIN (identical)

Topics in This Module