What type of relationship exists when an entity is involved with itself?

A recursive relationship occurs when an entity has a relationship with itself, allowing for scenarios where the same type of entity can participate in multiple relationships with different instances of that type. This is particularly useful in situations where the hierarchy or structure within the same entity type is present, such as in an organizational chart where an employee reports to another employee or a category that can include subcategories of the same type.

For example, consider a "Employee" entity where one employee might be a manager to another employee. This self-referencing capability allows for the modeling of complex relationships that involve a single entity, capturing hierarchical relationships or other interactions within the same entity type.

In contrast, other types of relationships like one-to-many and many-to-many involve interactions between different entities rather than self-referencing within a single entity type. A hierarchical relationship, while it might seem relevant, usually describes a tree structure where the relationships are defined through parent-child connections but does not specifically denote the self-referential nature as explicitly as a recursive relationship does.