File Organization Terms and Concepts

• Bit:Bit: Smallest unit of data; binary digit Smallest unit of data; binary digit (0,1)(0,1)

• Byte:Byte: Group of bits that represents a Group of bits that represents a single charactersingle character

• Field:Field: Group of words or a complete Group of words or a complete numbernumber

ORGANIZING DATA IN A TRADITIONAL FILE ENVIRONMENT

• Record:Record: Group of related fieldsGroup of related fields• File:File: Group of records of same typeGroup of records of same type• Database:Database: Group of related filesGroup of related files

• Entity:Entity: Person, place, thing, event about Person, place, thing, event about which information is maintainedwhich information is maintained

• Attribute:Attribute: Description of a particular entity Description of a particular entity

• Key field:Key field: Identifier field used to retrieve, Identifier field used to retrieve, update, sort a recordupdate, sort a record

File Organization Terms and ConceptsORGANIZING DATA IN A TRADITIONAL FILE ENVIRONMENT

Data Hierarchy in a Computer System

Figure 7-1

ORGANIZING DATA IN A TRADITIONAL FILE ENVIRONMENT

THE DATABASE APPROACH TO DATA MANAGEMENT

DBMS - a software that permits DBMS - a software that permits

Database Management System (DBMS)

to centralize data,to centralize data,

manage them efficiently,manage them efficiently,

provide access to data by application programprovide access to data by application program

acts as an interface between application program & data fileacts as an interface between application program & data file

Database- Database- a collection of data organized to a collection of data organized to serve many applications efficiently by serve many applications efficiently by centralizing the data and minimizing centralizing the data and minimizing redundant data redundant data

THE DATABASE APPROACH TO DATA MANAGEMENT

Database Management System (DBMS)Application

ProgramsDBMS Data file

Pay roll

Software

Oracle

8i

D:\database\employee.ora

HRM

Software

Provident Fund

Management

Software

Components of DBMS

• Data definition language: Data definition language: Specifies Specifies content and structure of database and content and structure of database and defines each data elementdefines each data element

• Data manipulation language:Data manipulation language:Manipulates data in a databaseManipulates data in a database

• Data dictionary:Data dictionary: Stores definitions of Stores definitions of data elements, and data characteristicsdata elements, and data characteristics

THE DATABASE APPROACH TO DATA MANAGEMENT

Relational DBMS

• Represents data as two-dimensional tables Represents data as two-dimensional tables called relationscalled relations

• Relates data across tables based on common Relates data across tables based on common data elementdata element

• Examples: DB2, Oracle, MS SQL ServerExamples: DB2, Oracle, MS SQL ServerMS-Access, MS-Visual FoxProMS-Access, MS-Visual FoxPro

THE DATABASE APPROACH TO DATA MANAGEMENT

• Entity-relationship diagram:Entity-relationship diagram: Methodology Methodology for documenting databases illustrating for documenting databases illustrating relationships between database entitiesrelationships between database entities

• Normalization:Normalization: Process of creating small Process of creating small stable data structures from complex groups stable data structures from complex groups of dataof data

CREATING A DATABASE ENVIRONMENT

Designing Databases

The Orders to ItemsSold relationship enforces referential integrity.

One Order can list many ItemsSold.

Data warehouseData warehouse

• Supports reporting and query toolsSupports reporting and query tools

• Stores current and historical data Stores current and historical data

• Consolidates data for management analysis Consolidates data for management analysis and decision makingand decision making

Data Warehousing and Datamining

DATABASE TRENDS

Components of a Data Warehouse

DATABASE TRENDS

DataminingDatamining

• Tools for analyzing large pools of data Tools for analyzing large pools of data

• Find hidden patterns and infer rules to Find hidden patterns and infer rules to predict trendspredict trends

Data Warehousing and DataminingDATABASE TRENDS