Database Models in DBMS

Database model is a conceptual tool for describing, data relationships, data semantics and consistency constraints. Data model defines how data is stored and how data is interrelated.

Record based data model

(i) Hierarchical data model

In hierarchical data model, each entity has only one parent but each entity can have multiple children (attribute). At the top of hierarchy there is only one entity called root.

For example,

(ii) Network data model

In network data model, records are linked to each other. Records are represented in graph.

For example,

Here course and college is linked to student.

(iii) Relational Model 

Relational model is a most popular data model. A relational data model is a collection of tables to represent data and relationship among data. Each table has columns and row. Every column represents attribute and each row represents a record. Every table in a database has a number of attributes of different type. The table in a relational model can be normalized.

For example,

This table contains records of faculty and their courses. This table has four attributes Faculty ID, Faculty Name, Faculty Hire Date and Course Code.

Entity - Relationship Model

Entity - Relationship Model is based on real world objects called entity and relationship among these objects called attribute.

For example,

Entity: Entity is a real world object. For example, school, bank etc.

Attribute: Entity can be defined by the part of their relationship called attribute. For example, roll_no, student name are attributes for entity school.