DBTG Quiz: Database Task Group and Schema Flashcards

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Questions and Answers

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

It allows for optimal navigation through the database (correct)

It simplifies complex relationships

It enables automated query optimization

It promotes database integrity

What is a drawback of the Network Model?

System complexity (correct)

Promotes database integrity

Limited scope for data abstraction

Lack of conformance to standards

Who is credited with developing the Relational Model?

E.F. Codd (correct)

C.J. Date

D.D. Chamberlin

M.M. Zloof

What is a characteristic of the Network Model's database structure?

A complex array of pointers threading through a set of records Signup and view all the answers

What is a limitation of the Network Model?

Little scope for automated query optimization Signup and view all the answers

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

To establish database standards and facilitate database creation Signup and view all the answers

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

Defines database components that will be used by application programs Signup and view all the answers

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

Set Signup and view all the answers

What is an advantage of the Network Model?

Ability to model complex relationships and represent semantics of add/delete on the relationships Signup and view all the answers

What is the function of Data Definition Language (DDL) in the Database Task Group (DBTG) report?

Enables database administrator to define schema components Signup and view all the answers

What is the equivalent of the hierarchical model’s parent in the Network Model?

Owner Signup and view all the answers

What is Crow’s Foot and Chen notation used for?

For graphical representation Signup and view all the answers

What is the concept where objects in a class hierarchy inherit the attributes and methods of classes above them?

Inheritance Signup and view all the answers

What is the main disadvantage of the Entity-Relationship Model?

Limited constraint representation Signup and view all the answers

What was the basis for the object-oriented database management system (OODBMS)?

Object-oriented data model (OODM) Signup and view all the answers

What is an advantage of the Object-Oriented Model?

Adds semantic content Signup and view all the answers

Why did Object-Oriented Data Model (OODM) become popular?

Growing costs put a premium on code reusability Signup and view all the answers

Study Notes

Network Model

Developed as an extension of the hierarchical model
Handles more relationship types
Offers data access flexibility
Promotes database integrity
Conforms to standards
Language is navigational, using constructs like FIND, FIND member, FIND owner, FIND NEXT within set, GET, etc.

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 in 1970
First commercial system in 1981-82
Objectives:
- Represent complex data relationships more effectively than the hierarchical model
- Improve database performance
- Establish database standards
Crucial database components:
- Schema: Conceptual organization of entire database
- Subschema: Defines database portion seen by application programs
- Data Management Language (DML): Defines data characteristics and data structure
- Schema Data Definition Language (DDL): Enables database administrator to define schema components
- Subschema DML: Allows application programs to define database components

Entity Relationship Model

Basic structure:
- Collection of records in 1:M relationships
- Relationship is called a Set: Owner and Member
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 row in the table
- Entity set is collection of entities at any time
- Connectivity labels types of relationships
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
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:
- Described by its factual content (Like relational model’s entity)
- Includes information about relationships between facts within object and relationships with other objects
Advantages:
- Adds semantic content
- Visual presentation includes semantic content
- Database integrity
- Both structural and data independence
- Persistent programming languages based OODB target applications that have high performance requirements

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Description

Learn about the Database Task Group (DBTG) and its role in establishing database standards. Understand the components of a database, including schema, and how they improve data relationships and performance.