1. Database Design - Lecture 1
Database Concepts

2. Lecture Objectives Data vs Information Historical Roots of Databases
What is a database, what it does, and why database design is important
What a DBMS is, what it does, and how it fits into the database system

3. Data vs Information Information System Data versus Information
Encompasses logic, algorithms and data
Transformation of data into useful information
Data versus Information
Data constitute building blocks of information
Information produced by processing data
Good, timely, relevant information key to decision making
Good decision making key to organization’s survival

4. Data vs Information

5. Data vs Information

6. Historical Roots of Databases
First applications focused on clerical tasks
File systems developed to address needs
Data organized according to expected use
Data Processing (DP) specialists computerized manual file systems
Requests for information quickly followed
Large amounts of data
Many users require simultaneous access

7. Historical Roots of Databases
Original databases applications:
Inventory Control
Payroll
Banking
Reservation Systems
Newer database applications:
CAD/CAM
GPS systems

8. File System Critique File System Data Management
Requires extensive programming in third-generation language (3GL)
Time consuming
Makes ad hoc queries impossible
Leads to islands of information

9. File System Critique (con’t.)
Data Dependence
Change in file’s data characteristics requires modification of data access programs
Must tell program what to do and how
Makes file systems cumbersome from programming and data management views
Structural Dependence
Change in file structure requires modification of related programs

10. File System Critique (con’t.)
Field Definitions and Naming Conventions
Flexible record definition anticipates reporting requirements
Selection of proper field names important
Attention to length of field names
Use of unique record identifiers

11. File System Critique (con’t.)
Data Redundancy
Different and conflicting versions of same data
Results of uncontrolled data redundancy
Data anomalies
Modification
Insertion
Deletion
Data inconsistency
Lack of data integrity

12. Introducing the Database
Data is stored in a database and must be structured and arranged for storage, extraction and processing
Database consists of a collection of logically related data stored in a single repository which consists of end user data and metadata

13. Database Management
A Database Management System (DBMS) manages the access to the database (and ultimately the data)
Database Management System (DBMS):
Collection of programs that manages database structure and controls access to data
Sharing of data among multiple applications and users

14. Importance of DBMS Makes data management more efficient and effective
Query language allows quick answers to ad hoc queries
Provides better access to more and better-managed data
Promotes integrated view of organization’s operations
Reduces the probability of inconsistent data

15. DBMS Manages Interaction
Figure 1.2

16. Importance of a DBMS For Top Management
Provides the information necessary for strategic decision making and strategic planning
Provides access to external and internal data
Provides information on company performance and whether they are achieving their goals (targets)

17. Importance of a DBMS For Middle Management
Provides data necessary for tactical decisions and planning
Provides a framework for enforcing and ensuring the security and privacy of the data

18. Importance of a DBMS For Operational Management
Provides timely information for customer support
Produce query results within specified performance levels
Represents and supports the company operations as closely as possible (operational data)

19. Database Design Importance of Good Design Practical Approach
eliminates data redundancy
eliminates errors leading to bad decisions
Practical Approach
Focus on principles and concepts of database design
Importance of logical design

20. Database vs. File Systems
Figure 1.6

21. Database System Environment
Figure 1.7

22. DBMS environment roles
Database Administrators
Responsible for:
Physical implementation of the DBMS
Security and integrity control of the DBMS
Maintenance of the operational system
Ensuring satisfactory performance of the applications for users
Requires detailed knowledge of the target DBMS and the system environment

23. DBMS environment roles
Database Designer
Logical Database Designer
Responsible for:
Identifying the data (entities and attributes)
Identifying the relationships between the data
Identifying the constraints on the data
Ensures that the direction of database development ultimately supports corporate objectives

24. DBMS environment roles
Database Designer
Physical Database Designer
Decides how the logical database design is to be physically realized
Responsible for:
Mapping the logical database design into a set of tables and integrity constraints
Selecting specific storage structures and access methods for the data to achieve good performance
Designing any security measures required on the data

25. Database System Types Single-user vs. Multiuser Database
Single-user desktop
Multi-user workgroup
Enterprise
Centralized vs. Distributed

26. Database Uses Production or transactional
Supports day-to-day operations
Decision support or data warehouse
Information for tactical or strategic decision making
Historical Data

27. DBMS Functions Data dictionary management Data storage management
Defines data elements and their relationships
Data storage management
Stores data and related data entry forms, report definitions, etc
Data transformation and presentation
Translates logical requests into commands to physically locate and retrieve the requested data

28. DBMS Functions Security management Multi-user access control
Enforces user security and data privacy within database
Multi-user access control
Creates structures that allow multiple users to access the data
Backup and recovery management
Provides backup and data recovery utilities

29. DBMS Functions Data integrity management
Promotes and enforces integrity rules to eliminate data integrity problems
Database language and application programming interfaces
Provides data access through a query language
Database communication interfaces
Allows database to accept end-user requests within a computer network environment

30. Where do we go from here?
Data Modeling

31. Where do we go from here?
Data Modeling