Read this SQL tutorial to learn when to use SELECT, JOIN, subselects and UNION to access multiple tables with a single statement.

A join combines two or more tables side by side. If you do not specify how to join the tables, you get a Cartesian product. This means that SQL combines each row from the first table with every row ...

The phrase FROM Donors INNER JOIN DonationRecords ON tells SQL to find matching records between the two tables, based on the expression that follows the key word ON.