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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
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