Flashcards
ER Modeling
Cards in this deck (7)
- 1What is an attribute?An attribute describes a property of an entity or a relationship. For example, "student" might have the attributes "id, age, major".
- 2Explain what is being conveyed here. What are the constraints?Each employee works in at most one department.
- 3Explain what is being conveyed here. What are the constraints?Each employee can manage at most one department.
Each department is managed by at most one employee.
- 4True or false: A weak entity cannot be uniquely identified without the candidate key of its owner entity.False. A weak entity cannot be uniquely identified without the PRIMARY key of its owner entity.
- 5The relationship between an owner entity and a weak entity is ___ to ___.one to many (one owner, many weak entities)
- 6True or false: By default, ISA hierarchies do not enforce covering constraints.True
- 7True or false: By default, overlap between inheriting entities in an ISA hierarchy is allowed.False. Such overlap is disallowed by default.