Describe relational data model with example

A data model is a collection of conceptual tools for describing data, data relationship, data semantics and consistency constraints. A data model provides a way to describe the design of a database at the physical, logical and view level.

Data models can be classified into following different categories:

(i) Relational Model: This is a lower level model. It uses a collection of tables to represent both data and relationships among those data.

•    Each table has multiple columns, and each column has a unique name.

•   The relational model is an example of a record-based model. This is because the database is structured in fixed-format records of several types. Each table contains records of a particular type. Each record type defines a fixed no. of fields, or attributes. The columns of the table correspond to the attributes of the record type.

•  The relational model is the most widely used data model and a vast majority of current database systems are based on the relational model.

(a) Customer Table

Customer-id	Customer-name	Customer-street	Customer-city
001-568	Mahiya	26 main street	Harrison
001-568	Hiphop	07 park Ave	Rye
045-195	Soshcho	19 north street	Palo alto
045-652	Bappa	26 alma street	Pitts field

(b) Account Table

Account_number	Balance
A-102	5462
A-217	6465
A-215	5646
A-256	78754

(c) Depositor Table

Customer_name	Account_number
Mahiya	A-126
Hiphop	A-107
Soshcho	A-119
Bappa	A-222
Hiphop	A-127

Figure: A sample relational database

(ii) Entity-Relationship Model: This is a higher-level data model. It is based on a perception of a real world that consists of a collection of basic objects, called entities and the relationship among these objects. An entity is a “thing” or “object” in the real word that is distinguishable from all other objects. The entity relationship model is widely used in database design.

(iii) Other Data Models:

• Object-Based Data Model:

(a) Object-oriented data model: Drawing increasing attention. It can be seen as extending or E-R model with notions of encapsulation, methods (functions) and object identity.

(b) Object-relation data model: Combines the features of object-oriented data model and relational data model.