Unit 4: Database Design & Development
Introduction and DB Environment
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By the end of this session a student will be able to learn:
▪ File Oriented Systems and Database Systems
▪ Components of a Database System
▪ Database Management System and Functions
▪ Data Dictionary/Directory (Repository) & Meta Data
▪ Database Applications
▪ Database Architecture
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File Processing System
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File Processing System - Issues
• Data Redundancy
• Data Inconsistency
• Data not Shareable
• Data Dependence
• Data Isolation
• Difficult to access and manipulate data
• Less data security
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What is Database system
(Introduction)
▪ A database is a collection of information that is organized so that it can
easily be accessed, managed, and updated.
▪ A shared collection of logically related data, and a description of this
data, designed to meet the information needs of an organization.
▪ A database to be a collection of related data and the Database
Management System (DBMS) to be the software that manages and
controls access to the database.
▪ A database application is simply a program that interacts with the
database at some point in its execution.
Ishani Jayasuriya - DDD - RQF
Types of Databases and
Database Applications
▪ Numeric and Textual Databases
▪
Banks
▪ Multimedia Databases
▪
Amazon. Com
▪ Geographic Information Systems (GIS)
▪ Data Warehouses
Ishani Jayasuriya - DDD - RQF
EXAMPLES
▪ Purchases from the supermarket
▪ Purchases using your credit card
▪ Booking a holiday at the travel agents
▪ Using the local library
▪ Taking out insurance
▪ Renting a video
▪ Using the Internet
▪ Studying at university
Ishani Jayasuriya - DDD - RQF
Database System Features
• Minimal data redundancy
• Data Consistency
• Data Shareable
• Data independence
• Data Integration.
• Easy to access and manipulate data
• High data security
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Components of Database System
• Hardware
• Software
• DBMS
• Application Software
• People
• Users
• Practitioners
• Data
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DBMS & Functions
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Data Dictionary
▪ A subsystem that keeps track of the definitions of all
data items in the database, relationships that exists
between various data structures, Indexes that are used
to access data quickly, screen and report format
definitions that may be used by various application
programs.
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Meta Data
▪Data Describes data
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Data warehouses
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Data warehouses
• Stores data that have been extracted from the various
operational, external and other databases
• A central source of the data that have been cleaned,
transformed, catalogued
• Can use for data mining, online analytical processing ,market
research and decision support
• A database for historical data
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Data mining
• It is an information-analysis tool that involves the automated
discovery of hidden patterns and trends in historical business
activity.
• It helps to extract patterns and trends
• Turn will improve competitiveness, improve profits and
transform business processes.
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Data Marts
• A sub set of a data warehouse.
• Store a subset of the data for a single aspect of a company
• Example: Finance, inventory, personnel
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Distributed Databases
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Distributed database
• Data spread across several databases connected through
telecommunications devices.
• The user does not need to have knowledge about the physical
location of the database.
• DBMS finds the location of data according to the user
requirement.
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Database Architecture
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Mapping
▪ The processes of transforming requests and results between
levels are called mappings. There are two levels of mapping in
the architecture, one between the external and conceptual
levels of the system and one between the conceptual and
internal levels.
1. External/conceptual mapping
2. Conceptual/internal mapping
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Data Independence
▪ The three-schema architecture can be used to explain the
concept of data independence, which can be defined as the
capacity to change the schema at one level of a database
system without having to change the schema at the next higher
level.
1. Logical Data Independence
2. Physical Data Independence
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Thank You !
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