Join Operations

JOIN operations are fundamental to working with relational databases. They allow you to combine rows from two or more tables based on related columns.

Types of JOINs

INNER JOIN

Returns only matching rows from both tables:

SELECT books.title, authors.first_name
FROM books
INNER JOIN authors ON books.author_id = authors.author_id;

LEFT JOIN

Returns all rows from the left table and matching rows from the right:

SELECT customers.first_name, orders.order_date
FROM customers
LEFT JOIN orders ON customers.customer_id = orders.customer_id;

RIGHT JOIN

Returns all rows from the right table and matching rows from the left.

FULL OUTER JOIN

Returns all rows when there’s a match in either table.

Understanding JOINs is crucial for effective database querying!