What are SQL join commands and how do they work?

What are SQL join commands and how do they work?

SQL join commands 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?

Absolutely! Suppose you have two tables: 'Customers' and 'Orders'. An INNER JOIN would look like this: SELECT Customers.Name, Orders.OrderID FROM Customers INNER JOIN Orders ON Customers.CustomerID = Orders.CustomerID; This will return only the customers who have placed orders.

What about a LEFT JOIN example?

For a LEFT JOIN, you could use: SELECT Customers.Name, Orders.OrderID FROM Customers LEFT JOIN Orders ON Customers.CustomerID = Orders.CustomerID; This will return all customers, including those who haven't placed any orders, with NULL for the OrderID.