This video explains how to use the SELECT statement of the Structured Query Language (SQL) to query more than one table at a time, by means of JOINS. It is the fifth in a series about a subset of SQL known as the Data Manipulation Language (DML), which is used to work with the data in database tables. It includes examples of how to use the INNER JOIN, LEFT OUTER JOIN, RIGHT OUTER JOIN, FULL OUTER JOIN and CROSS JOIN. It explains the meanings of these join expressions and the role of the ON clause when specifying the relationship between a pair of tables.