What are SQL joins and how do I use them in queries?

What are SQL joins and how do I use them in queries?

SQL joins are used to combine rows from two or more tables based on a related column. There are different types of joins like INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN.

Can you explain the difference between INNER JOIN and LEFT JOIN?

Sure! INNER JOIN returns only the rows that have matching values in both tables, while LEFT JOIN returns all rows from the left table and the matched rows from the right table. If there's no match, NULL values are returned for columns from the right table.

Can you give me an example of an INNER JOIN query?

Absolutely! Here's an example: SELECT a.name, b.order_id FROM customers a INNER JOIN orders b ON a.id = b.customer_id; This query retrieves customer names and their corresponding order IDs.

What about a LEFT JOIN example?

Sure! Here's a LEFT JOIN example: SELECT a.name, b.order_id FROM customers a LEFT JOIN orders b ON a.id = b.customer_id; This will return all customers and their order IDs, showing NULL for customers without orders.