Read this SQL tutorial to learn when to use SELECT, JOIN, subselects and UNION to access multiple tables with a single statement. It’s sometimes difficult to know which SQL syntax to use when ...

Key points: INNER JOIN → returns rows with matching values in both tables LEFT JOIN → returns all rows from the left table and matched rows from the right table RIGHT JOIN → returns all rows from the ...

You often need data that are stored in separate tables. For example, you may want to produce a report that gets information about flight delays from one table and boarding capacity from another.