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Which relationship is shown in the following diagram?
The given diagram represents a unary relationship (also called a recursive relationship), which occurs when an entity is related to itself. In this case, salespersons back each other up, meaning a salesperson is associated with another salesperson from the same entity.
Key Observations from the Diagram:
Single Entity (Salesperson)
The table contains only one entity type, Salesperson, which has attributes such as Salesperson Number, Name, Commission, Percentage, and Year of Hire.
Self-Referencing Relationship (Backs-up and Backed-up by)
The diagram shows that a salesperson can back up another salesperson.
This means that the relationship exists within the same entity rather than between two different entities.
Cardinality (One-to-One Relationship in a Unary Form)
The notation ( |---| ) in the ER diagram indicates a one-to-one recursive relationship.
One salesperson can back up only one other salesperson, and each salesperson is backed up by only one.