SQL JOIN Types Guide

Example:

INNER JOIN:
SELECT * FROM orders o
INNER JOIN customers c ON o.customer_id = c.id

LEFT JOIN:
SELECT * FROM customers c
LEFT JOIN orders o ON c.id = o.customer_id

Complete guide to SQL JOINs: INNER JOIN (matching rows), LEFT JOIN (all left + matches), RIGHT JOIN (all right + matches), FULL OUTER JOIN (all rows).

Try SQL Beautifier →

FAQs

When to use LEFT vs INNER JOIN?

Use INNER JOIN for matching rows only. Use LEFT JOIN to keep all left table rows even without matches.