How do LEFT JOIN and RIGHT JOIN operations differ in SQL, and in which situations should each be used?

LEFT JOIN and RIGHT JOIN are types of table joins in SQL that allow combining data from two tables based on a condition.

• LEFT JOIN returns all rows from the left table and the matching rows from the right table. If there are no matches in the right table, the right table's fields will be filled with NULL.
• RIGHT JOIN returns all rows from the right table and the matching rows from the left table. If there are no matches in the left table, the left table's fields will be NULL.

Usage:

• Use LEFT JOIN when you want to get all data from the main (left) table and supplement it with information from the related table if available.
• Use RIGHT JOIN when the main table is the right one, and you want to get all its data, supplementing it from the left.

In practice, LEFT JOIN is more common because usually the main table is on the left.

Example:

SELECT a.id, a.name, b.order_date
FROM customers a
LEFT JOIN orders b ON a.id = b.customer_id;

Here, we will get all customers and their orders if they exist.