1. ORGANIZING DATA IN A TRADITIONAL FILE ENVIRONMENT
File Organization Terms and Concepts
Bit: Smallest unit of data; binary digit (0,1)
Byte: Group of bits that represents a single character
Field: Group of words or a complete number

2. ORGANIZING DATA IN A TRADITIONAL FILE ENVIRONMENT
File Organization Terms and Concepts
Record: Group of related fields
File: Group of records of same type
Database: Group of related files

3. ORGANIZING DATA IN A TRADITIONAL FILE ENVIRONMENT
Data Hierarchy in a Computer System
Figure 7-1

4. ORGANIZING DATA IN A TRADITIONAL FILE ENVIRONMENT
File Organization Terms and Concepts
Entity: Person, place, thing, event about which information is maintained
Attribute: Description of a particular entity
Key field: Identifier field used to retrieve, update, sort a record

5. ORGANIZING DATA IN A TRADITIONAL FILE ENVIRONMENT
Entitities and Attributes
Figure 7-2

6. ORGANIZING DATA IN A TRADITIONAL FILE ENVIRONMENT
Traditional File Processing
Figure 7-3

7. Program-Data dependence Lack of flexibility Poor security
ORGANIZING DATA IN A TRADITIONAL FILE ENVIRONMENT
Problems with the Traditional File Environment
Data redundancy
Program-Data dependence
Lack of flexibility
Poor security
Lack of data-sharing and availability

8. DATA REDUNDANCY The presence of duplicate data in multiple data files
Different functions collect the same information independently
May have different meanings in different parts of the organisation

9. Data Redundancy 7

10. Data Redundancy
Staff_Branch relation has redundant data; the details of a branch are repeated for every member of staff.
In contrast, the branch information appears only once for each branch in the Branch relation and only the branch number (Branch_No) is repeated in the Staff relation, to represent where each member of staff is located. 8

11. Program Data Dependence
The tight relationship between data stored in files and the specific programs required to update and maintain those files
Every program must describe the nature
In traditional file environment any changes to data requires a change in all programs that access the data
A change in tax rates for example !!

12. Lack of Flexibility
Traditional File system can deliver routine scheduled reports after a significant programming efforts
An ad hoc/ unanticipated request for information, would require a lot of time
The information is somewhere in the system but too expensive to locate/retrieve
Compiling the data could take weeks

13. Poor Security There is little or no control and management of data
Data could be disseminated all over the organisation without control
Who is accessing the data and making changes?

14. Lack of Data-sharing Lack of control over access
Hard to get hands on information
Different pieces of information in different files and different physical locations
Since files in different locations can’t be related hard to share or access in a timely manner
Impossible for information to flow freely

15. Database Technology DATABASE:
A collection of data organised to serve many applications efficiently by centralising the data and minimising redundant data.

16. Historical context Why develop DBMS at all?
Manage flood of data from Transaction Processing Systems
Integrate data across organisation
“Data glare”

17. DBMS Create, delete, reorganize, and manipulate data in a database
A Database Management System (DBMS) is general purpose software and hardware facility to:
Create, delete, reorganize, and manipulate data in a database
Store, retrieve, share, and maintain data in a database
Maintain relationships between the database components

18. Creates and maintains databases
THE DATABASE APPROACH TO DATA MANAGEMENT
Database Management System (DBMS)
Creates and maintains databases
Eliminates requirement for data definition statements
Acts as interface between application programs and physical data files

19. DBMS Cont’d
Provide security and procedures relating to privilege and access.
Authenticates the integrity of all the updates and transactions that are carried out.
interface for the access, deletion and addition of data and for redefining the relationships within the database.
A DBMS is a collection of programs that manages the database structure and controls access to the data stored in the database.

20. DBMS
Relieves the programmer or end user from the task of understanding where and how data are actually stored
Seperates the logical view from the physical view
Logical View- How data perceived by end users or business specialists
Physical View- How data is actually organised and structured on phsical storage media

21. THE DATABASE APPROACH TO DATA MANAGEMENT
The Contemporary Database Environment
Figure 7-4

22. Hierarchical and Network DBMS Object-Oriented Databases
THE DATABASE APPROACH TO DATA MANAGEMENT
Types of Databases
Relational DBMS
Hierarchical and Network DBMS
Object-Oriented Databases

23. Represents all data in DB as two-dimensional tables called relations
THE DATABASE APPROACH TO DATA MANAGEMENT
Relational DBMS
The most popular type of DBMS today for PCs as well as for larger companies and mainframes
Represents all data in DB as two-dimensional tables called relations
Similar to flat files but information in more than one file can easily be extracted and combined
Relates data across tables based on common data element
Examples: DB2, Oracle, MS SQL Server

24. Relational Data Model Figure 7-6
THE DATABASE APPROACH TO DATA MANAGEMENT
Relational Data Model
Figure 7-6

25. Select: Creates subset of rows that meet specific criteria
THE DATABASE APPROACH TO DATA MANAGEMENT
Three Basic Operations in a Relational Database
Select: Creates subset of rows that meet specific criteria
Join: Combines relational tables to provide users with information
Project: Enables users to create new tables containing only relevant information

26. Three Basic Operations in a Relational Database
THE DATABASE APPROACH TO DATA MANAGEMENT
Three Basic Operations in a Relational Database
Figure 7-7

27. Hierarchical DBMS Organizes data in a tree-like structure
THE DATABASE APPROACH TO DATA MANAGEMENT
Hierarchical and Network DBMS
Hierarchical DBMS
Organizes data in a tree-like structure
Supports one-to-many parent-child relationships
Prevalent in large legacy systems

28. THE DATABASE APPROACH TO DATA MANAGEMENT
Hierarchical DBMS
Figure 7-8

29. Hierarchical Disadvantages Knowledge of physical level required
Does not support logical data independence and does not support all physical data independence operations
Not all problems are one-to-many types
Problems with multiple parent implementation
Problems with anomalies for parent deletion
Application development in 3GL time-consuming
Support programs are not part of the DBMS
“System created by programmers for programmers!”

30. Network DBMS Depicts data logically as many-to-many relationships
THE DATABASE APPROACH TO DATA MANAGEMENT
Network DBMS
Depicts data logically as many-to-many relationships

31. THE DATABASE APPROACH TO DATA MANAGEMENT
Network DBMS

32. Disadvantages Outdated Less flexible compared to RDBMS
THE DATABASE APPROACH TO DATA MANAGEMENT
Disadvantages
Outdated
Less flexible compared to RDBMS
Lack support for ad-hoc and English language-like queries

33. Object-Oriented databases
Object-oriented DBMS: Stores data and procedures as objects that can be retrieved and shared automatically
Object-relational DBMS: Provides capabilities of both object-oriented and relational DBMS

34. DBMS Disadvantages DBMSs are complex;
Need for explicit backup and control;
Costs associated with development and operation can be substantial;
Consolidation of an entire business’ information resources can create a high level of vulnerability.

35. Designing Databases
Conceptual design: Abstract model of database from a business perspective
Physical design: How data is actually stored on direct access storage devices

36. CREATING A DATABASE ENVIRONMENT
Designing Databases
Entity-relationship diagram: Methodology for documenting databases illustrating relationships between database entities
Normalization: Process of creating small stable data structures from complex groups of data

37. An Entity-Relationship Diagram
Figure 7-10

38. An Unnormalized Relation of ORDER
Figure 7-11

39. An Normalized Relation of ORDER
Figure 7-12

40. Distributing Databases
Centralized database
Used by single central processor or multiple processors in client/server network

41. Distributing Databases
Distributed database
Stored in more than one physical location
Partitioned database
Duplicated database

42. Distributed Databases
Figure 7-13

43. Data warehouse Supports reporting and query tools
DATABASE TRENDS
Data Warehousing and Datamining
Data warehouse
Supports reporting and query tools
Stores current and historical data
Consolidates data for management analysis and decision making

44. Components of a Data Warehouse
DATABASE TRENDS
Components of a Data Warehouse
Figure 7-16

45. Datamining Tools for analyzing large pools of data
DATABASE TRENDS
Data Warehousing and Datamining
Datamining
Tools for analyzing large pools of data
Find hidden patterns and infer rules to predict trends

46. Improved and easy accessibility to information
DATABASE TRENDS
Benefits of Data Warehouses
Improved and easy accessibility to information
Ability to model and remodel the data

47. Database server Application server
DATABASE TRENDS
Databases and the Web
Database server
Computer in a client/server environment runs a DBMS to process SQL statements and perform database management tasks
Application server
Software handling all application operations

48. Linking Internal Databases to the Web
DATABASE TRENDS
Linking Internal Databases to the Web
Figure 7-18