What relationship type is characterized by an entity referencing itself?

The relationship type characterized by an entity referencing itself is referred to as a recursive relationship. This type of relationship occurs when an entity in a database is associated with itself in some way. For example, consider an employee database where each employee can have a supervisor who is also an employee. In this case, the Employee entity refers back to itself to indicate the hierarchical relationship between employees and their supervisors.

The term "recursive" effectively captures the nature of this relationship because it implies that the same entity type is involved multiple times in the relationship, allowing for complex structures such as organizational hierarchies, bill of materials in manufacturing, or parts in a product assembly.

The other choices do not appropriately describe this concept. "Self-referential" could imply something similar but does not have the same formal definition in database terminology. "Circular" and "Bidirectional" generally suggest different types of relationships where entities relate in ways that are not specifically defined by them referencing themselves directly. Thus, "recursive" is the most precise term to describe an entity that references itself within its own structure.