INNER JOIN: definition and application
The INNER JOIN is the most important JOIN type in the relational database model. If you want to query database tables in a group, you would usually use INNER JOINs based on equality relationships between primary and foreign keys. We will show you how to use INNER JOINs in practice, delineate the JOIN type from OUTER JOINs, and also deal with the different subtypes of INNER JOINs.