Itqualityassurance
The disjoint rule states an entity instance of a supertype can only be a member of one subtype. The overlap rule states an entity instance of a supertype can be a member of multiple subtypes.
- What is disjoint and overlapping rule?
- What is disjoint in database?
- What is overlapping in DBMS?
- What is disjoint and partial?
What is disjoint and overlapping rule?
The disjoint rule forces subclasses to have disjoint sets of entities. The overlap rule forces a subclass (also known as a supertype instance) to have overlapping sets of entities. Completeness constraints - decide whether a supertype instance must also be a member of at least one subtype.
What is disjoint in database?
In a disjoint specialization, also called an exclusive specialization, an individual of the parent class may be a member of only one specialized subclass. In an overlapping specialization, an individual of of the parent class may be a member of more than one of the specialized subclasses.
What is overlapping in DBMS?
Two or more instances of the super class are participating in two or more sub classes then it is called overlapping constraints.
What is disjoint and partial?
Total-Disjoint- All the instances coming, will map to one subclass only and will not be shared among other subclasses. Partial-Disjoint- All instances coming, may stay with superclass or map to one of the sub classes only. Total-Overlap- All instances coming, will map to multiple subclasses.
