Page 68 - CITS - Computer Software Application -TT

COMPUTER SOFTWARE APPLICATION - CITS

2 Attributes: Attributes provide descriptions or characteristics of an entity. These can include properties like
name, age, roll number, or any other relevant information. In an ER Diagram, attributes are symbolized using
ovals or ellipses.
3 Relationship: Relationships define connections between various entities. They represent how different entities
are related to each other in the real world. In an ER Diagram, relationships are indicated using diamonds or
rhombuses.

2 Representational Data Model
This type of data model is used to represent only the logical part of the database and does not represent the
physical structure of the database. The representational data model allows us to focus primarily, on the design
part of the database. A popular representational model is a Relational model. The relational Model consists of
Relational Algebra and Relational Calculus. In the Relational Model, we basically use tables to represent our
data and the relationships between them.
3 Physical Data Model
The Physical Data Model serves the practical implementation of the Relational Data Model. In the end, all
database data is physically stored on secondary storage devices like disks and tapes. This storage occurs
in the form of files, records, and other specific data structures. This model encompasses details about file
formats, database structure, external data structure presence, and their interrelationships.
Advantages of Data Models
1 Accurate Data Representation: Data models ensure precise and structured representation of data, enhancing
its clarity and organization.
2 Data Integrity and Minimized Redundancy: Data models aid in identifying missing data and reducing
redundancy by maintaining consistent and non-repetitive data entries.
3 Enhanced Data Security: Data models contribute to improved data security measures, safeguarding
information against unauthorized access or tampering.
4 Effective Physical Database Creation: A well-designed data model should offer sufficient detail to serve as
a foundation for constructing the physical database, ensuring alignment between the conceptual and physical
levels.
5 Relationship Definition: Data models support the delineation of relationships between tables, as well as the
establishment of primary and foreign keys. This is crucial for maintaining data consistency and integrity.
6 Stored Procedure Definition: The information encapsulated in a data model can be utilized to define stored
procedures, enabling efficient data manipulation and retrieval.
Disadvantages of Data Models
1 Complexity with Large Databases: In the context of extensive databases, comprehending the intricacies of
the data model can become challenging and overwhelming.

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CITS : IT&ITES - Computer software application - Lesson 18 - 36