1. Chapter 1 1 DATABASE ENGINEERING INTRODUCTION

2. Chapter 1 2 DATABASE ENGINEERING EC-316 Credits4(3,1) Text Book: Modern Database Management, by Hoffer, Prescott, MsFadden, 2008, Latest Edition Grading Criteria: –Sessional60% Assignments:8% Quizzes:10% Sessional 1:20% Sessional 2:20% Project:8% Practical34% –Final 40%

3. Chapter 1 3 The Database Environment

4. Chapter 1 4 Topics Growth and importance of databases Limitations of conventional file processing

5. Chapter 1 5 Definitions

6. Chapter 1 6 Database (Definition) In the broadest sense, a database is anything that stores data. A phone book, for instance, could be considered a database as it stores related pieces of information such as name and phone number. However, in the world of computers, a database usually refers to a collection of related pieces of information stored electronically. Aside from the ability to store data, a database also provides a way for other computer programs to quickly retrieve and update desired pieces of data. Reference: http://www.mariosalexandrou.com/definition/database.asp

7. Chapter 1 7 Database (Definition) A database is an application that manages data and allows fast storage and retrieval of that data. R eference http://cplus.about.com/od/glossar1/g/databasedefn.htm

8. Chapter 1 8 Database (Definition) A database is a collection of information that is organized so that it can easily be accessed, managed, and updated. Reference: http://searchsqlserver.techtarget.com/sDefinition/0,,sid87 _gci211895,00.html

9. Chapter 1 9 Definitions (By Hoffer) Database (Concluded): organized collection of logically related data Data: stored representations of meaningful objects and events –Structured: (data in tabular (table,array,spreadsheet)form) i.e numbers, text, dates. –Unstructured/multimedia data: (found on webservers & web enabled data bases; requires more storage space) images, video,maps,sound, documents. Information: The data which is processed in such a way that knowledge of the person who uses data is increased.

10. Chapter 1 When Data Becomes Useful Information Data: When data is placed in some context(). When data is summarized or processed & presented in such a way that it is easily interpretable by the human. 10

11. Chapter 1 11 Figure 1-1a Data in context Context helps users understand data

12. Chapter 1 12 Graphical displays turn data into useful information that managers can use for decision making and interpretation Figure 1-1b Summarized data

13. Chapter 1 Metadata Data that describes the properties of user data( data names,definitions,length or size,allowable values ) and context of user data( source of data, where data is stored,ownership,usage ). 13

14. Chapter 1 14 Descriptions of the properties or characteristics of the data, including data types, field sizes, allowable values, and data context

15. Chapter 1 15 Disadvantages of File Processing Program-Data Dependence –All programs maintain metadata for each file they use Duplication of Data –Different systems/programs have separate copies of the same data Limited Data Sharing –No centralized control of data Lengthy Development Times –Programmers must design their own file formats Excessive Program Maintenance –80% of information systems budget

16. Chapter 1 16 Problems with Data Dependency Each application programmer must maintain his/her own data Each application program needs to include code for the metadata of each file Each application program must have its own processing routines for reading, inserting, updating, and deleting data Lack of coordination and central control Non-standard file formats

17. Chapter 1 17 Figure 1-3 Old file processing systems at Pine Valley Furniture Company Duplicate Data

18. Chapter 1 18 Problems with Data Redundancy Waste of space to have duplicate data Causes more maintenance headaches The biggest problem: –Data changes in one file could cause inconsistencies –Compromises in data integrity