Context: The relational model also allowed the content of the database to evolve without constant rewriting of links and pointers. The relational part comes from entities referencing other entities in what is known as one-to-many relationship, like a traditional hierarchical model, and many-to-many relationship, like a navigational (network) model. Thus, a relational model can express both hierarchical and navigational models, as well as its native tabular model, allowing for pure or combined modeling in terms of these three models, as the application requires.

Question: How was the relational model able to improve over time?
Answer: without constant rewriting of links and pointers

Question: What is the relationship called in a hierarchical model?
Answer: one-to-many

Question: What is the relationship called in a navigational model?
Answer: many-to-many

Question: What is a third type of model that can be combined with heirarchical and navigation models?
Answer: tabular

Question: How was the relational model able to degrade over time?
Answer: Unanswerable

Question: What is the only kind of relationship called?
Answer: Unanswerable

Question: What is the relationship that is avoided in a navigational model?
Answer: Unanswerable

Question: What is a third type of model that can't be combined with hierarchical and navigation models?
Answer: Unanswerable