INNER JOIN:
Definition: Returns only the rows that have matching values in both tables.
Use Case: To find customers who have placed orders.

Example: Selecting customers and their orders where the order exists.
LEFT JOIN:
Definition: Returns all rows from the left table and the matched rows from the right table. If no match, NULL values are returned for columns from the right table.
Use Case: To list all customers and their orders, including those who haven’t placed any orders.

Example: Selecting all customers and their orders, showing NULL for customers without orders.
RIGHT JOIN:
Definition: Returns all rows from the right table and the matched rows from the left table. If no match, NULL values are returned for columns from the left table.Use Case: To find all orders and the customers who placed them, including orders without a customer (e.g., orders made by guest users).

Example: Selecting all orders and the customers who placed them, showing NULL for customers not in the customer table.