DBTG and Database Standards

InsightfulOboe avatar
InsightfulOboe
·

Start Quiz

Study Flashcards

17 Questions

What is a benefit of the navigational language in the Network Model?

Optimal navigation through the database

What is a disadvantage of the Network Model?

System complexity

Who developed the Relational Model?

E.F.Codd

What is a characteristic of the Network Model?

Navigational and procedural

What is a limitation of the Network Model?

Little scope for automated query optimization

What is the primary objective of creating the Network Model?

To improve database performance and impose a database standard

What is the function of the Subschema in the Database Task Group (DBTG) report?

Defines the database portion seen by application programs

What is the term used to describe the relationship between records in the Network Model?

Set

What is the advantage of the Network Model in terms of data relationships?

Ability to model complex relationships and represents semantics of add/delete on the relationships

What is the purpose of the Database Task Group (DBTG) created by the Conference on Data Systems Languages (CODASYL)?

To define standard specifications for a database creation environment

What is the role of the Data Management Language (DML) in the Network Model?

Defines data characteristics and data structure

What is the purpose of Chen Notation?

Representing entity relationships graphically

What is the limitation of the Entity Relationship Model?

All of the above

What is the key feature of the Object-Oriented Data Model?

Abstraction of real-world entities with operations

What led to the popularity of Object-Oriented Data Modeling?

Cost savings through code reusability

What is the benefit of the Object-Oriented Model?

Data independence and integrity

What is the purpose of classes in the Object-Oriented Model?

To group objects with similar characteristics

Study Notes

Network Model

  • Developed as an alternative to the hierarchical model
  • Handles more relationship types than the hierarchical model
  • Provides data access flexibility and promotes database integrity
  • Conforms to standards
  • Uses navigational language with constructs like FIND, FIND member, FIND owner, FIND NEXT within set, GET, etc.
  • Allows programmers to navigate optimally through the database

Disadvantages of Network Model

  • Navigational and procedural nature of processing
  • System complexity
  • Lack of structural independence
  • Database contains a complex array of pointers that thread through a set of records
  • Little scope for automated "query optimization"

Relational Model

  • Developed by E.F. Codd (IBM) in 1970
  • First commercial system in 1981-82
  • Created to represent complex data relationships more effectively than the hierarchical model
  • Improves database performance
  • Imposes a database standard

Crucial Database Components (DBTG report)

  • Schema: Conceptual organization of entire database as viewed by the database administrator
  • Subschema: Defines database portion seen by application programs that produce desired information from data contained within the database
  • Data Management Language (DML): Defines data characteristics and data structure in order to manipulate the data
  • Schema Data Definition Language (DDL): Enables database administrator to define schema components
  • Subschema DDL: Allows application programs to define database components that will be used
  • DML: Manipulates database contents

Network Model Basic Structure

  • Resembles hierarchical model
  • Collection of records in 1:M relationships
  • Relationship is called a Set: Set is composed of at least two record types
  • Owner: Equivalent to the hierarchical model’s parent
  • Member: Equivalent to the hierarchical model’s child

Network Model Advantages

  • Ability to model complex relationships and represents semantics of add/delete on the relationships
  • Crow’s foot and Chen Notations can be used for graphical representation
  • Entity is mapped to a relational table
  • Entity instance (occurrence) is a row in the table
  • Entity set is a collection of entities at any time
  • Connectivity labels types of relationships
  • Diamond connected to related entities through a relationship line
  • Relationships are expressed using Chen notation
  • Relationship name is written inside the diamond

Entity Relationship Model

Advantages

  • Exceptional conceptual simplicity
  • Visual representation
  • Effective communication tool
  • Integrated with the relational data model

Disadvantages

  • Limited constraint representation
  • Limited relationship representation
  • No data manipulation language
  • Loss of information content

Object-Oriented Model

  • Developed by Hammer and McLeod in 1981 as a semantic data model (SDM)
  • Modeled both data and their relationships in a single structure known as an object
  • Basis of object-oriented data model (OODM)
  • OODM becomes the basis for the object-oriented database management system (OODBMS)
  • Object is described by its factual content
  • Includes information about relationships between facts within object and relationships with other objects
  • Subsequent OODM development allowed an object to also contain operations
  • Object becomes basic building block for autonomous structures

Object-Oriented Model Basic Structure

  • Object: abstraction of a real-world entity, contains operations and is self-contained and forms a basic building-block for autonomous structures
  • Attributes describe the properties of an object
  • Objects that share similar characteristics are grouped in classes
  • Classes are organized in a class hierarchy
  • Inheritance is the ability of an object within the class hierarchy to inherit the attributes and methods of classes above it

Advantages of Object-Oriented Model

  • Adds semantic content
  • Visual presentation includes semantic content
  • Database integrity
  • Both structural and data independence
  • Persistent programming languages based OODB target applications of that form that have high performance requirements

Learn about the objectives of the Database Task Group (DBTG) and its role in establishing database standards. Discover how DBTG improves database performance and represents complex data relationships. Explore the crucial components of a database according to the DBTG report.

Make Your Own Quizzes and Flashcards

Convert your notes into interactive study material.

Get started for free
Use Quizgecko on...
Browser
Browser