COMPUTER SCIENCE AND ENGINEERING
DATABASE MANAGEMENT SYSTEM
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
Cardinality
|
|
|
Composite entity
|
|
|
Optional relationships
|
|
|
Business rules
|
Detailed explanation-1: -Cardinality refers to the maximum number of times an instance in one entity can relate to instances of another entity. Ordinality, on the other hand, is the minimum number of times an instance in one entity can be associated with an instance in the related entity.
Detailed explanation-2: -The cardinality of a relationship is the number of related rows for each of the two objects in the relationship. The rows are related by the expression of the relationship; this expression usually refers to the primary and foreign keys of the underlying tables.
Detailed explanation-3: -A relationship where two entities are participating is called a binary relationship. Cardinality is the number of instance of an entity from a relation that can be associated with the relation.
Detailed explanation-4: -Low cardinality refers to a database that has a lot of repeated values like status flags, Boolean values, or gender. In contrast, high cardinality refers to a database that has a large number of distinct values such as ID numbers, user names or email addresses.