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Note for Database Management System - DBMS by gunjan dashore

  • Database Management System - DBMS
  • Note
  • Rajiv Gandhi Proudyogiki Vishwavidyalaya Bhopal - rgpv
  • Computer Science Engineering
  • B.Tech
  • 4 Topics
  • Uploaded 2 years ago
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2. Relational Model  Relational model is based on first-order predicate logic.  This model was first proposed by E. F. Codd.  It represents data as relations or tables.  Relational database simplifies the database structure by making use of tables and columns. 3. Network Database Model  Network Database Model is same like Hierarchical Model, but the only difference is that it allows a record to have more than one parent.  In this model, there is no need of parent to child association like the hierarchical model.  It replaces the hierarchical tree with a graph.  It represents the data as record types and one-to-many relationship.

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 This model is easy to design and understand. 4. Entity Relationship Model  Entity Relationship Model is a high-level data model.  It was developed by Chen in 1976.  This model is useful in developing a conceptual design for the database.  It is very simple and easy to design logical view of data.  The developer can easily understand the system by looking at an ER model constructed. In this diagram,  Rectangle represents the entities. Eg. Doctor and Patient.  Ellipse represents the attributes. Eg. DocId, Dname, PId, Pname. Attribute describes each entity becomes a major part of the data stored in the database.  Diamond represents the relationship in ER diagrams. Eg. Doctor diagnoses the Patient.

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5. Object Model  Object model stores the data in the form of objects, classes and inheritance.  This model handles more complex applications, such as Geographic Information System (GIS), scientific experiments, engineering design and manufacturing.  It is used in File Management System.  It represents real world objects, attributes and behaviors.  It provides a clear modular structure.  It is easy to maintain and modify the existing code.

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Database Normalization Introduction to Normalization  Normalization is a process of organizing the data in the database.  It is a systematic approach of decomposing tables to eliminate data redundancy.  It was developed by E. F. Codd.  Normalization is a multi-step process that puts the data into a tabular form by removing the duplicate data from the relation tables.  It is a step by step decomposition of complex records into simple records.  It is also called as Canonical Synthesis.  It is the technique of building database structures to store data. Definition of Normalization “Normalization is a process of designing a consistent database by minimizing redundancy and ensuring data integrity through decomposition which is lossless.” Features of Normalization  Normalization avoids the data redundancy.  It is a formal process of developing data structures.  It promotes the data integrity.  It ensures data dependencies make sense that means data is logically stored.  It eliminates the undesirable characteristics like Insertion, Updation and Deletion Anomalies.

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