Chapter 1 Essay

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Copyright © 2007 Ramez Elmasri and Shamkant B. Navathe

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Chapter 1
Introduction: Databases and
Database Users

Copyright © 2007 Ramez Elmasri and Shamkant B. Navathe

Outline









Types of Databases and Database Applications
Basic Definitions
Typical DBMS Functionality
Example of a Database (UNIVERSITY)
Main Characteristics of the Database Approach
Database Users
Advantages of Using the Database Approach
When Not to Use Databases

Copyright © 2007 Ramez Elmasri and Shamkant B. Navathe

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Types of Databases and Database
Applications


Traditional Applications:




More Recent Applications:









Numeric and Textual Databases
Multimedia Databases
Geographic Information Systems (GIS)
Data Warehouses
Real-time and Active Databases
Many other applications

First part of book focuses on traditional applications
A number of recent applications are described later in the book (for example, Chapters 24,26,28,29,30)
Copyright © 2007 Ramez Elmasri and Shamkant B. Navathe

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Basic Definitions










Database:
 A collection of related data.
Data:
 Known facts that can be recorded and have an implicit meaning.
Mini-world:
 Some part of the real world about which data is stored in a database. For example, student grades and transcripts at a university. Database Management System (DBMS):
 A software package/ system to facilitate the creation and maintenance of a computerized database.
Database System:
 The DBMS software together with the data itself. Sometimes, the applications are also included.

Copyright © 2007 Ramez Elmasri and Shamkant B. Navathe

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Simplified database system environment

Copyright © 2007 Ramez Elmasri and Shamkant B. Navathe

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Typical DBMS Functionality






Define a particular database in terms of its data types, structures, and constraints
Construct or Load the initial database contents on a secondary storage medium
Manipulating the database:






Retrieval: Querying, generating reports
Modification: Insertions, deletions and updates to its content
Accessing the database through Web applications

Processing and Sharing by a set of concurrent users and application programs – yet, keeping all data valid and consistent Copyright © 2007 Ramez Elmasri and Shamkant B. Navathe

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Typical DBMS Functionality


Other features:






Protection or Security measures to prevent unauthorized access
“Active” processing to take internal actions on data
Presentation and Visualization of data
Maintaining the database and associated programs over the lifetime of the database application 

Called database, software, and system maintenance Copyright © 2007 Ramez Elmasri and Shamkant B. Navathe

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Example of a Database
(with a Conceptual Data Model)


Mini-world for the example:




Part of a UNIVERSITY environment.

Some mini-world entities:






STUDENTs
COURSEs
SECTIONs (of COURSEs)
(academic) DEPARTMENTs
INSTRUCTORs

Copyright © 2007 Ramez Elmasri and Shamkant B. Navathe

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Example of a Database
(with a Conceptual Data Model)


Some mini-world relationships:









SECTIONs are of specific COURSEs
STUDENTs take SECTIONs
COURSEs have prerequisite COURSEs
INSTRUCTORs teach SECTIONs
COURSEs are offered by DEPARTMENTs
STUDENTs major in DEPARTMENTs

Note: The above entities and relationships are typically expressed in a conceptual data model, such as the
ENTITY-RELATIONSHIP data model (see Chapters 3, 4)
Copyright © 2007 Ramez Elmasri and Shamkant B. Navathe

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Example of a simple database

Copyright © 2007 Ramez Elmasri and Shamkant B. Navathe

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Main Characteristics of the Database
Approach


Self-describing nature of a database…