Introduction to Database
Prepared By :
Topics To Be Covered
Introduction about Database.Characteristics of the database approach. Actors on the scene.
Workers behind the scene. Introduction to DBMS.
Advantages of using a DBMS.
Structured And Unstructured data
– Flat file = unstructured data – Database = structured data
• The Problem with Unstructured Data
High maintenance costs
Data Redundancy: the same data will be represented multiple times in the file.
Data dependence: if you change things about the file format then there will be expensive changes to programs that use it.
Database
Data = facts and figures
Information = processed data.
A database is a collection of data, typically describing the activities of one or more related organizations. For example, a university database might contain information about the following:
Entity:
A database contains one or more related tables.
Each table holds all of the information about an object, person or thing. Some examples of database tables might be:
- a customer table
- an appointments table - an exam sessions table - a teachers' names table - a concert venue table
Basic Definition
• 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
Database System
Application program
End-user
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
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 could be expressed in the
Characteristics Of Database
In file system each applications is free to name data element
independently. Each user define and implements the file needed for a specific software application as a part of programming the
application.
In database a single repository of data is maintained that is defined once and than accessed by various users.
Typical DBMS Functionality
•
Define a database : in terms of data types, structures
and constraints
•
Construct or Load the Database on a secondary
storage medium
•
Manipulating the database : querying, generating
reports, insertions, deletions and modifications to its
content
•
Concurrent Processing and Sharing by a set of users
Typical DBMS Functionality
Other features:
▫
Protection or Security measures to prevent
unauthorized access
▫
“Active” processing to take internal actions on data
Actor on the scene
A person typically defines, constructs, and manipulates the database. In large organization, many people are responsible in the design, use and maintenance of a large database with hundreds of user.
We call these users as the actors on the scene.
Database Administrator. Database Designer.
Database Administrator
In any organization where many people use the same resources,
there is a need for a chief administrator to oversee and manage these resources.
In a database environment, the primary resource is the database itself, and the second resource is the DBMS and related software. Administrating these resources is the responsibility of the database administrator (DBA).
Database Designer
Database designer are responsible for
identifying the data to be stored in the data and for choosing appropriate structures to
represent and store this data.
These task should be done before the database actually implemented and populated with data. It is the responsibility of the database
End Users
End users are the people whose job require access to the database for querying, updating and generating reports;
There are four kinds of end users:
Casual User:
These kinds of user occasionally access the database, but they may need different information each time. They use database queries query language to specify their requests.
Naive and Parametric Users:
End Users (cont.)
Example of Naive and Parametric users are
Bank tellers check account balances and post withdrawals and deposits.
Reservation clerks for airlines, hotels, and cars rental companies check availability for a given request and make reservations.
Sophisticated End Users:
It include engineers, scientist, business analyst who are familiar with the DBMS in order to implement their applications.
Standalone Users:
Workers Behind the Scene
DBMS system designers and implementers:
These people design and implement the DBMS module and interfaces as a software packages.
A DBMS consist of complex components or modules for implementing the catalogue, processing query language, controlling concurrency and handling data recovery and security.
Tool Designer:
Workers behind the scene (cont.)
Operators and Maintenance Personal:
Database Management System-DBMS
Database Management System.
A database management system, or DBMS, is software designed to assist in
maintaining and utilizing large collections of data, and the need for such systems, as well as their use, is growing rapidly.
Database Management system – Management of data and Management of Users
Software package for defining and managing a database.
Examples:
Proprietary: MS Access, MS SQL Server, DB2, Oracle, Sybase
Implication Of Using The Database Approach
Potential for Enforcing Standards:
In large organization certain standards are made in order to facilitate communication and co-operation among various departments, projects, and users within the organization.
Standards can be defined for names and formats of data elements, display formats, report structures, terminology and so on.
Reduced Application Development Time:
Designing a database from scratch takes more time than a flat file system, however once the database is created, it is so easy to retrieve data from the database.
Flexibility:
It may be necessary to change the structure of the database with the inclusion of new entities. Nowadays DBMS allow certain types of evolutionary changes to the structure of the
Implication of the Database Approach(cont.)
Availability Of Up-to-Date Information:
DBMS make the update database available to all users. It is so important at some industries to retrieve the updated database.
The availability is essential for many transaction-processing applications, such as reservation systems or banking database.
Economies Of Scale:
The DBMS approach permits consolidation of data and applications.
Advantages of Database
• Reduction of redundancy.
Avoid storing the data multiple times.
• Restricting Unauthorized Access.
• Avoidance of inconsistency.
• Provide Storage Structure for efficient Query Processing
• Share ability.
• Provide Backup and Recovery.
• Provide Multiuser interface.
• Representing Complex Relationship among Data.
• Enforcing Integrity Constraint.
Integrity constraint involves specifies a data type for each item.
Uniqueness in data- a course_name should have different course name.
Disdvantages of Database
Higher cost
Conversion cost
When Not To Use Database
In spite of advantages of using the database, there are some situation in which a DBMS may involve unnecessary overheads. Some of them are listed below:
High initial investment in hardware, software and training.
The generality that a DBMS provides for defining and processing the data. Overheads for providing the security, concurrency control, recovery, and integrity functions.
Problem arise when the database are not properly design.
Application Of Database Management System.
Hospital Management System.
Hotel Management System.
Flight Aviation Management
University Management System.
Summary
Introduction
Basic definitions
Database Data
Mini world DBMS
Database systems
An example database
Applications of database
Advantages Of Database
Functionalities of database systems
