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

Figure A We’ll use these two tables to demonstrate how JOINs affect your queries. Notice that the Donors table contains five records, each representing a different person.

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 ...