a relationship that relates a field in one database to a field in the same database

a table that joins upon itself

A join that compares rows within the same table. For example, you can use a self-join to find all publishers that are in the same city and have the same postal code. In database diagrams, a self-join is called a reflexive relationship.

A join in which records from a table are combined with other records from the same table when there are matching values in the joined fields. A self-join can be an inner join or an outer join. In database diagrams, a self-join is called a reflexive relationship.

In a query, a table that is related to itself by two different fields. For example, an employee table can include the ID of a manager who is also in the same table.