DataBase

• Metadata


  Data that is about data. It is the way in which the database keeps information about its own structure.
• Pre-Database Information System


  • Data are separated and isolated
  • Data are often duplicated
  • Application programs are dependent on file formats
  • Files are often incompatible with one another
  • It is difficult to represent data in a user's perspective
• Database System


  • Integrated data
  • Reduced data duplication
  • Program/data independence
  • Easier representation of users' perspectives
  • Database systems are self-describing
  • Database systems maintain program-data independence
  • A database is a model of a model
• Differences between File Processing System and Database System

  • File Processing System: Integrated data, Data are separated and isolated, Data are often duplicated, Application programs are dependent on file formats, Files are often incompatible with one another, It is difficult to represent data in a user's perspective
  • Database System: Reduced data duplication, Program/data independence, Database systems are self-describing, Easier representation of users' perspectives
• Database System in Detail

  1. Customer Processing Application

  2. Rental Processing Application

  3. Other Application

  4. Database

  5. Database Management System

  6. User
• Common Applications


  • Forms
  • Reports
  • Web-applications
  • Batch processes
• DBMS Functions


  • CRUD functions
  • Data dictionary
  • Transaction management
  • Concurrency control
  • Recovery
  • Authorisation
  • Data communication
  • Data integrity
  • Administration utilities
• Advantages of DBMS - 1

  • Control of data redundancy
  • Data consistency
  • More information from the same amount of data
  • Sharing of data
  • Improved data integrity
  • Improved security
  • Enforcement of standards
• Advantages of DBMS - 2

  • Economy of scale
  • Balance of conflicting requirements
  • Improved data accessibility and responsiveness
  • Increased productivity
  • Improved maintenance through data independence
  • Increased concurrency
  • Improved backup and recovery services
• Disadvantages of DBMS - 2

  • Complexity
  • Size
  • Cost of DBMSs
  • Additional hardware costs
  • Cost of conversion
  • Performance
  • Higher impact of a failure
• Market Share of Commercial Products

  • MySQL 29%
  • Oracle 23%
  • MS Access / Sql SERVER 24%
  • DB2 10%
  • Others 14%
• Commercial Implementations


  • Oracle
  • MySQL
  • Microsoft SQL Server
• Learning Outcomes - Revisited


  • Describe the main features of a database system
  • Understand the role of the database management system
  • Describe pre-database information systems
  • Identify some of the commercial products available
  • Understand the importance of the relational model and identify some alternatives to it
• List of Topics


  • Introduction to the module and database fundamentals
  • Databases and Database Management Systems (DBMS)
  • Entity Relationship (ER) Modelling (1)
  • Entity Relationship (ER) Modelling (2)
  • The relational model (1)
  • The relational model (2)
  • SQL (1)
  • SQL (2)
  • Database Design
  • Supporting transactions
  • Database implementation
  • Summary
• Information Technology


  The use of computers to store, retrieve, transmit, and manipulate data or information
• Components of Information Technology

  • Software
  • Hardware
  • Application
  • Networks
  • Internet
  • Database
• Where use Database?


  • Purchasing using a credit card
  • Using the Internet
  • Using a Library
  • Studying at College or University
  • Using Facebook
• Health Insurance


  1. Collate the relevant data about the person

  2. Store this data somewhere

  3. Match the data to data about types of insurance

  4. If searching from more than one company, then this might be on multiple databases

  5. Matching people to insurance might use an Expert System
• Database Functions


  • Store
  • Retrieve (Select)
  • Manipulate (Update/Delete)
• Database Size


  • Single user databases on a PC
  • Small office database with everyone doing the same sorts of tasks
  • Medium size database system with core data but people doing different tasks
  • Corporate databases spread over many sites
  • Very large databases and data-warehouses
• Database


  An organised collection of logically related data
• Topics covered


  • Database Fundamentals
  • Database and DBMS
  • Entity Relationship Modelling
• Database


  • Data is structured so as to be easily stored, manipulated and retrieved by users
  • Pieces of data do not exist in isolation
• Types of Data


  • Text
  • Numbers
  • Dates
  • Images
  • Sounds
  • Video
  • Scans of documents
• Database


  A collection of data that is organized so that its contents can easily be accessed, managed, and updated
• Data and Information


  Data is raw facts and figures, information is data that has been processed into a meaningful form
• Data

  Raw facts
• Information


  Data that has been processed and given meaning
• DBMS functions


  • Organize data
  • Store data
  • Manage data
  • Retrieve data
• Different Between Data and Information
• Entity Relationship Modelling


  A technique for conceptual database design
• Information is Important
• DBMS advantages


  • Data independence
  • Data integrity
  • Data security
  • Concurrency control
  • Backup and recovery
• Topics in Entity Relationship Modelling 1

  • Goal of Entity Relationship Modelling
  • Entity
  • Relationship
  • Attributes
  • Multiplicity
  • Types of attributes
  • Approach for identifying entities
• Topics in Entity Relationship Modelling 2

  • Constructing ER models
  • Primary and Foreign keys
  • Strong and weak entities
  • Identifying problems in ER models
  • Problem solving in ER models
• Relationship


  The meaningful associations between entity types
• Foreign Key


  Links entities into relationships
• Identifying Entities


  1. Look for nouns

  2. Top down (from ERD)

  3. Bottom up (from normalization)
• Types of Entity


  • Objects
  • People
  • Types
  • Concepts
  • Others
• Entity Types and Attributes - 1

  • Student
  • Module