Introduction to Data Management

Chapter 1, Pratt & Adamski

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.

Knowledge Generation

DATA

INFORMATION

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.

DefineConstructManipulate

Advantages of Database Processing

More information from same data

Shared dataBalancing conflicts

among usersControlled

redundancyConsistency

IntegritySecurityIncreased

productivityData

independence

Disadvantages of Database Processing

Increased sizeIncreased complexity

More expensive personnelIncreased impact of failureDifficulty of recoveryCost

Especially server and mainframe systems

Objectives of the DBMS Approach

SELF-DESCRIBINGDATA INDEPENDENCEMULTIPLE VIEWSMULTIPLE USERS

What is a Database Management System?

Data FilesDirectory

Access EngineUtility Programs

UTILITIES

ACCESS ENGINE

METADATA

Database

DATA

Files and Databases

Metadata “Data about data”

Description of fieldsDisplay and format instructionsStructure of files and tablesSecurity and access rulesTriggers and operational rules

Database Access

DATABASE

PROGRAM

USER INTERFACE

History of Database Management

File Management SystemsHierarchical ModelIBM “Information Management System (IMS)” 1966

Network ModelCharles Bachman’s “Integraded Data Store (IDS)”

1965Conference on Data Systems Languages /DataBase

Task Group CODASYL/DBTG (1971)

Relational ModelE.F. Codd, 1970

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.

Database vs File Systems

Program 1

Program 2

Program 3

Meta-Data

Meta-Data

Meta-Data

Data

Program 1

Program 2

Program 3

Meta- Data

Data

FILE SYSTEM

DATABASE

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.

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.

STUDENT

SECTION

INSTRUCTOR

Hierarchy

COLLEGECOLLEGE

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

STUDENT

SECTION

INSTRUCTOR

Network

COLLEGE

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

SECTION

Relational

COLLEGE

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

STUDENTCOLLEGE-KEY

INSTRUCTORCOLLEGE-KEY

SECTION-STUDENTSECTION-KEYSTUDENT-KEY

SECTION-INSTRUCTORSECTION-KEYINSTRUCTOR-KEY

Relational Terminology

Entity Person, place, thing or event about

which we wish to keep dataAttribute

property of an entityRelationship

an association among entities (entity records)

KERR MCGEE’S LIFE CYCLE

STAGE PROCESS MODEL DATA MODEL

Initialization Report Report

Feasibility ReportHigh Level DFD

Process Analysis (Business Chart)High Level E/R Diagram

Requirements General

DFDHigh Level Dictionary

Top Down E/RFile Specifications

Requirements Logical

DFDData DictionaryFile SpecificationsProcess Logic

Bottom Up E/RAction Diagrams

System Design Structure ChartsModule IPO SpecificationScreen/Report LayoutsCleanup

Volume/Usage AnalysisPhysical SchemaIndex/Record Specs

Coding/Testing Test PlanLogs and DocumentationCode

Implementation Installation Plan Population Plan

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.

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.