bagian 1 managing data resources

8/14/2019 Bagian 1 Managing Data Resources

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Managing Data Resources


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Objectives

Definition of terms

Explain growth and importance of databases

Name limitations of conventional file processing

Identify categories of databases

Explain advantages of databases

Identify costs and risks of databases

List components of database environment

Describe evolution of database systems


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

Byte: Group of bits that represents a singlecharacter

Field: Group of words or complete number

Record: Group of related fields

File: Group of records of the same type

Organizing Data in a Traditional File Environment

File Organization Terms and Concepts


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Database: Group of related files

Entity: Person, place, thing, or event about which

information must be kept

Attribute: A piece of information describing aparticular entity

Key field: Field that uniquely identifies everyrecord in a file


File Organization Terms and Concepts


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The data hierarchy


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Entities and attributes


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Traditional file processing


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Problems with Data Dependency

Each application programmer must maintain theirown data

Each application program needs to include codefor the metadata of each file

Each application program must have its ownprocessing routines for reading, inserting, updatingand deleting data

Lack of coordination and central control Non-standard file formats


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Problems with Data Redundancy

Waste of space to have duplicate data

Causes more maintenance headaches The biggest problem:

When data changes in one file, could cause

inconsistencies Compromisesdata integrity


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Data redundancyDifferent systems/programs have separate copies of the same data

Program-data dependenceAll programs maintain metadata for each file they use

Lack of flexibilityProgrammers must design their own file formats

Poor security, lack of data-sharing and availabilityNo centralized control of data

Excessive Program Maintenance80% of of information systems budget


Problems with the Traditional File Environment


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Database

Collection of centralized data

Controls redundant data

Data stored so as to appear to users in one location

Services multiple application

The Database Approach to Data Management

Database Management Systems


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Definitions

Database: organized collection of logically related

data

Data: stored representations of meaningful objects

and events Structured: numbers, text, dates

Unstructured: images, video, documents

Information: data processed to increase knowledge inthe person using the data

Metadata: data that describes the properties and

context of user data


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Data in Context

Context helps users understand data


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Graphical displays turn data into useful

information that managers can use for decision

making and interpretation


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Metadata :Descriptions of the properties or

characteristics of the data, including data types, field

sizes, allowable values, and data context


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The contemporary database environment


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Database Management System (DBMS)

A software system that is used to create, maintain,

and provide controlled access to user databases

Creates and maintains databases

Eliminates requirement for data definition

statements

Acts as interface between application programsand physical data files

Separates logical and physical views of data




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Three Components to a DBMS

Data definition language: Formal language

programmers use to specify structure of database Data manipulation language: For extracting data

from database, e.g. SQL

Data dictionary: Tool for storing, organizingdefinitions of data elements and datacharacteristics




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Sample data dictionary report

Figure 7-5


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How a DBMS Solves Problems of a

Traditional File Environment

Reduces data redundancy Eliminates data inconsistency

Uncouples programs from data

Increases access and availability of data

Allows central management of data, data use, andsecurity




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Advantages of the Database Approach

Program-data independence

Minimal data redundancy

Improved data consistency

Improved data sharing

Increased productivity of application development

Enforcement of standards

Improved data quality

Improved data accessibility and responsiveness

Reduced program maintenance

Improved decision support


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Cost and Risk of the Database Approach

New, specialized personnel

Installation and management cost and complexity

Conversion costs

Need for explicit backup and recovery Organizational conflict


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Components of the

Database Environment

CASE Tools computer-aided software engineering

Repository centralized storehouse of metadata

Database Management System (DBMS) software for managingthe database

Database storehouse of the data

Application Programs software using the data

User Interface text and graphical displays to users

Data Administrators personnel responsible for maintaining the

database System Developers personnel responsible for designing databases

and software

End Users people who use the applications and databases


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Components of the

Database Environment


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Evolution of DB Systems

Flat files - 1960s - 1980s

Hierarchical 1970s - 1990s

Network 1970s - 1990s

Relational 1980s - present

Object-oriented 1990s - present

Object-relational 1990s - present

Data warehousing 1980s - present

Web-enabled 1990s present

Data mining 2000s - present

Evolution of Database Systems


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The three basic operations of a relational DBMS

Figure 7-7


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Hierarchical DBMS

Older system presenting data in tree-like structure

Models one-to-many parent-child relationships

Found in large legacy systems requiring intensive high-

volume transactions: Banks; insurance companies

Examples: IBMs IMS


Types of Databases


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A hierarchical database for a human resources system

Figure 7-8


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Network DBMS

Older logical database model

Models many-to-many parent-child relationships

Example: Student course relationship: Each

student has many courses; each course has manystudents


Types of Databases


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The network data model

Figure 7-9


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Relational DBMS

Represents data as two-dimensional tables calledrelations

Relates data across tables based on common data

element Examples: DB2, Oracle, MS SQL Server


Types of Databases


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The relational data model


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Three Basic Operations in a RelationalDatabase

Select: Creates subset of rows that meet specificcriteria

Join: Combines relational tables to provide userswith information

Project: Enables users to create new tablescontaining only relevant information


Types of Databases


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Object-Oriented Databases (OODBMS)

Stores data and procedures as objects

Better able to handle graphics and recursive data

Data models more flexible

Slower than RDBMS

Hybrid: object-relational DBMS


Types of Databases


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Data Mining at Fingerhut Inc.Fingerhut published about 25 different catalogs, but shipped onlythe general merchandise catalog monthly and tracked customersbuying patterns and behaviors. If a customer bought cookware,first Fingerhut would follow up with specialized

Cooks Bookand More Houseware & cooking suppliescatalogs.Then telemarketers would call to follow up with new products.

Through customer data mining Fingerhut found that customers whorecently changed their residence were likely to triple their purchasingin the 12 weeks after their move, with a peak in buying in the first fourweeks. Their selections often followed a pattern new furniture,telecommunications equipment, and decorations but seldom jewelry orhome electronics. The company used this discovery to tailor a new"mover's catalog" to entice customers who recently moved.

bagian 1 managing data resources

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