Which of the following is a generic entity type that has a relationship with one or more subtypes? Show
Given the following entities, which of the choices below would be the most complicated? Automobile: VIN, EngineSize, NumberOfDoors,
NumberOfPassengers, FuelType, Transmission Define one vehicle entity type to hold all entities. The property by which subtype entities possess the values of all attributes of a supertype is called: Subtypes should be used when: there are attributes that apply to some but not all instances of an entity type. The process of defining one or more subtypes of a supertype and forming relationships is called: The process of defining a more general entity type from a set of more specialized entity types is called: Which of the following is a completeness constraint? The ________ rule specifies that an entity instance of a supertype is allowed not to belong to any subtype. The ________ rule specifies that each entity instance of the supertype must be a member of some subtype in the relationship. A ________ constraint is a type of constraint that addresses whether an instance of a supertype must also be an instance of at least one subtype. The ________ rule specifies that an entity can be a member of only one subtype at a time. A ________ addresses whether an instance of a supertype may simultaneously be a member of two or more subtypes. disjointedness constraint Is the rule that specifies that an entity instance of a supertype may not simultaneously be a member of two or more subtypes?Disjoint rule. Specifies that if an entity instance (of the supertype) is a member of one subtype, it cannot simultaneously be a member of two (or more) subtypes. Overlap rule. Specifies that an entity instance can simultaneously be a member of two (or more) subtypes.
What rule specifies that each entity instance of the supertype must be a member of some subtype in the relationship?The disjoint rule specifies that if an entity instance of the supertype is a member of one subtype, it MUST simultaneously be a member of another subtype.
What type of constraints in Supertype that an instance of a supertype may simultaneously be a member of two or more subtypes?Disjointness Constraints: Whether an instance of a supertype may simultaneously be a member of two (or more) subtypes.
What type of constraints in Supertype that an instance of a supertype must also be a member of at least one subtype?Completeness Constraints: Whether an instance of a supertype must also be a p yp member of at least one subtype. b) Partial Specialization rule Figure 3-6 Examples of completeness constraints (cont.)
|
Rule specifies that an entity instance of a supertype is allowed not to belong to any subtype
zusammenhängende Posts
Urheberrechte © © 2024 ketiadaan Inc.
