Data Models

Data Model is the modeling of the data description, data semantics, and consistency constraints of the data. It provides the conceptual tools for describing the design of a database at each level of data abstraction.

Therefore, there are following four data models used for understanding the structure of the database:

• Relational Data Model

• Entity-Relationship Data Model

• Object-based Data Model

• Semi-structured Data Model

Relational Data Model

• This model was described by Edgar F. Codd, in 1969.

• Data are designed in rows and columns within a table.

• Tables are used to represent data and relationships.

• Tables are called relations.

• It is the widely used model by commercial data processing applications.

Entity-Relationship Data Model

• This model was designed by Peter Chen and published in 1976.

• It is the logical representation of data as objects and relationships.

• These objects are known as entities, and relationship is an association among these entities.

• A set of attributes describe the entities. For example, name, email, phone describes a person entity.

• A set of the same type of entities is known as an 'Entity set', and the set of the same type of relationships is known as 'relationship set'.

• It was widely used in database designing.

Object-based Data Model

• Object-based Data Model were developed in 1980s.

• It is an extension of the ER model with notions of functions, encapsulation, and object identity.

• Objects are data carrying its properties.

• It supports a rich type system that includes structured and collection types.

Semi structured Data Model:

• It is different from the other three data models.

• Same data items may have different attributes sets.

• The Extensible Markup Language (XML) is widely used to represent semi-structured data.