What is an association in database?
What is an association in database?
An association is a business component that defines a relationship between two entity objects based on common attributes. The relationship can be one-to-one, one-to-many, or many-to-many. The association allows entity objects to access the data of other entity objects through a persistent reference.
What is aggregation in DBMS?
Aggregation in DBMS (Database Management System) is a process of combining two or more entities to form a more meaningful new entity. Usually, an ETL tool will have the Aggregation option along with its other operations.
What are 3 types of cardinality ratios?
- One to one cardinality. When a single instance of an entity is associated with a single instance of another entity, then it is called as one to one cardinality.
- One-to-Many cardinality.
- Many-to-one cardinality.
- Many-to-many cardinality.
What is the difference between association and institution?
(1) Association refers to an organized group of people having definite aims. But institutions are forms of procedures and way of doing things. But institutions refers to a social condition of conduct and behavior. Because institutions consists of rules, regulations, laws and procedures.
What is multi valued attribute?
A multivalued attribute of an entity is an attribute that can have more than one value associated with the key of the entity. For example, a large company could have many divisions, some of them possibly in different cities.
What is Generalisation and Specialisation?
Generalization is the process of extracting shared characteristics from two or more classes, and combining them into a generalized superclass. In contrast to generalization, specialization means creating new subclasses from an existing class.
What is Generalisation and Specialisation in DBMS?
Specialization process starts from a single entity set and it creates a different entity set by using some different features. In Generalization, the difference and similarities between lower entities are ignored to form a higher entity. In Specialization, a higher entity is split to form lower entities.
