Entity Types and Relationships
There are many kinds of entity relationships in a database model. The relationships can be classified by the following things.
Cardinality: maximum and minimum
Degree: binary, ternary, degree 4, and so forth
Entity type: strong, weak, ID-dependent, and supertype/subtype
What are these different types of classifications? Do they overlap, or do they each tell us something unique about the entity relationship? Why is it important to classify each of these types in an ERD (entity relationship diagram) model?