SQL INNER JOIN vs LEFT JOIN

Joins combine data from multiple tables, but not all joins behave the same.

INNER JOIN

SELECT c.id, c.name, o.order_id
FROM customers c
INNER JOIN orders o ON c.id = o.customer_id;

• Returns only customers who have orders.

LEFT JOIN

SELECT c.id, c.name, o.order_id
FROM customers c
LEFT JOIN orders o ON c.id = o.customer_id;

• Returns all customers, even if they have no orders.

Key Difference

• INNER JOIN → Only matching rows
• LEFT JOIN → All from left table + matches

Tip: Use LEFT JOIN for reporting when you need ‘no match’ data as well.