1. Introduction to Data Management
Chapter 1, Pratt & Adamski
Delivered 8/20/98

2. Data and Information
DATA: Facts concerning people, objects, vents or other entities. Databases store data.
INFORMATION: Data presented in a form suitable for interpretation.
Data is converted into information by programs and queries. Data may be stored in files or in databases. Neither one stores information.
KNOWLEDGE: Insights into appropriate actions based on interpreted data.

3. Knowledge Generation
DATA
INFORMATION

4. Using a DBMS Data DBMS Engine Access Data Management Database Design
Metadata
DBMS Engine
Access
Direct access
Host language
Data Management

5. Basic Principles
DATABASE: A shared collection of interrelated data designed to meet the varied information needs of an organization.
DATABASE MANAGEMENT SYSTEM: A collection of programs to create and maintain a database.
Define
Construct
Manipulate

6. Advantages of Database Processing
More information from same data
Shared data
Balancing conflicts among users
Controlled redundancy
Consistency
Integrity
Security
Increased productivity
Data independence

7. Disadvantages of Database Processing
Increased size
Increased complexity
More expensive personnel
Increased impact of failure
Difficulty of recovery
Cost
Especially server and mainframe systems

8. Objectives of the DBMS Approach
SELF-DESCRIBING
DATA INDEPENDENCE
MULTIPLE VIEWS
MULTIPLE USERS

9. What is a Database Management System?
Data Files
Directory
Access Engine
Utility Programs

10. Database
DATA
METADATA
ACCESS ENGINE
UTILITIES

11. Files and Databases Metadata “Data about data” Description of fields
Display and format instructions
Structure of files and tables
Security and access rules
Triggers and operational rules

12. Database Access
USER
INTERFACE
DATABASE
PROGRAM

13. History of Database Management
File Management Systems
Hierarchical Model
IBM “Information Management System (IMS)” 1966
Network Model
Charles Bachman’s “Integraded Data Store (IDS)” 1965
Conference on Data Systems Languages /DataBase Task Group CODASYL/DBTG (1971)
Relational Model
E.F. Codd, 1970

14. File Management Systems
Provided facilities to extract data and share files, but did not implement any way to connect records in one file to those in another. Relationships had to be implemented in application code.

15. Database vs File Systems
Program 1
Meta-Data
Data
Program 2
Meta-Data
Program 3
Meta-Data
DATABASE
Program 1
Meta-
Data
Data
Program 2
Program 3

16. Structured Databases
Relationships were implemented by physical pointers (called “sets”) which allowed records to be connected in different files. Hierarchical databases allow only one parent set; networks allow several. These permit efficient processing but the sets must be constructed on data entry and cannot be rearranged later.

17. Relational Models
Relational models implement relationships with matched data values in related files (called primary and foreign keys). Any attributes can be matched. The connection is established at retrieval so interconnections can be developed as needed.

18. Hierarchy SECTION STUDENT INSTRUCTOR COLLEGE COLLEGE
Each file can have only one parent. To implement a second “parent” (COLLEGE) we have to implement a shadow copy.

19. Network SECTION STUDENT INSTRUCTOR COLLEGE
Each file can have several parents. Both SECTION and COLLEGE are “parent” files..

20. Relational SECTION SECTION-STUDENT SECTION-INSTRUCTOR STUDENT
SECTION-KEY
STUDENT-KEY
SECTION-INSTRUCTOR
SECTION-KEY
INSTRUCTOR-KEY
STUDENT
COLLEGE-KEY
INSTRUCTOR
COLLEGE-KEY
COLLEGE
Each file can have several parents. Both SECTION and COLLEGE are “parent” files..

21. Relational Terminology
Entity
Person, place, thing or event about which we wish to keep data
Attribute
property of an entity
Relationship
an association among entities (entity records)

22. Distribution Strategies for Databases
Centralized Data and Processing: Dumb terminal with "screen scraping".
Intelligent Terminal: Data and processing centralized; data preparation and display on remote devices.
Distributed Logic: Data storage distributed; processed at the optimal location. A version of parallel processing.
Client Server: Data (usually departmental) maintained on a server. Subsetting occurs on the server, processing on client machines.
Distributed Database: Data distributed among different locations; processing access data wherever it is located. Data may be replicated or partitioned.

25. Data Management
Designing and managing information in a data base environment requires:
Understanding the principles of data modeling in system design.
Using SQL for data manipulation.
Understanding the concepts of managing data in a database environment.

26. Information System Modeling Approaches
PROCESS MODELING: The traditional method of designing systems by following the changes to data flows.
DATA MODELING: An approach to system development that specifies the file structure that conforms to the things important to the organization.
PROTOTYPING: An iterative approach that focuses on building small operating
OBJECT MODELING (Event driven design):
Defines objects that contain data and associated processing rules encapsulated together.