self-join

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. For example, if you have an Employees table, you can create a self-join between the EmployeeID field in one instance of the Employees table and the ReportsTo field in another instance of the Employees table. You can then use this join to retrieve information about each employee's supervisor. A self-join can be an inner join or an outer join. A self-join is also known as a reflexive relationship.