How do SQL joins work in practice?

How do SQL joins work in practice?

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 give me an example of an INNER JOIN?

Sure! If you have a 'Customers' table and an 'Orders' table, an INNER JOIN would return only the customers who have placed orders. The SQL query would look like this: SELECT Customers.Name, Orders.OrderID FROM Customers INNER JOIN Orders ON Customers.CustomerID = Orders.CustomerID;

What about a LEFT JOIN?

A LEFT JOIN returns all records from the left table and the matched records from the right table. If there's no match, NULL values are returned for columns from the right table. For example: SELECT Customers.Name, Orders.OrderID FROM Customers LEFT JOIN Orders ON Customers.CustomerID = Orders.CustomerID;

How do I decide which type of join to use?

It depends on the data you need. Use INNER JOIN when you want only matching records, LEFT JOIN when you want all records from the left table regardless of matches, and so on.