Data and Information.ppt

8/14/2019 Data and Information.ppt

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Organizing Data and Information

DatabaseCollection of data organized to meet users needs

Database management system (DBMS)Software consisting of a group of programs thatmanipulate the database and provide an interface

between the database and the application programs


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The Hierarchy of Data

Data is generally organized in a hierarchy that begins with the smallest piece of data(a bit) and progresses through the hierarchy to a database.


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The Hierarchy of Data Cont. Character

Basic building block of information, represented by a byte(0,1)

FieldA name, number, or combination of characters thatdescribes an aspect of a business activity

Record

Collection of related fieldsFile

Collection of related recordsDatabase

Collection of integrated and related files


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Data Entities, Attributes, and Keys

EntityGeneralized class of people, places, or things for whichdata is collected, stored, and maintained

AttributeCharacteristic of an entity

Data itemSpecific value of an attribute

KeyA field or set of fields in a record that is used to identifythe record

Primary key

A field or set of fields that uniquely identifies a record


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Keys and Attributes

The Traditional Approach to Data Management

Data management in which separate data files are created and

stored for each application program


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The Traditional Approach to Data

Management


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Data redundancyDuplication of data in separate files

Data integrity

The degree to which the data in any one file is accurateProgram-data dependence

Potential for incompatible programs and data betweenapplications

Flaws in the Traditional Approach


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Data management in which a pool of related data isshared by multiple application programsRather than having separate data files, each application

uses a collection of data that are either joined or relatedin the database.

The Database Approach to DataManagement


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The Database Approach to Data

Management


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Advantages of the DatabaseApproach

Improved strategic use of corporate dataReduced data redundancyImproved data integrity

Easier modification and updatingData and program independenceBetter access to data and information

Standardization of data accessA framework for program developmentBetter overall protection of the data

Shared data and information resources


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Database Considerations Content

What data is to be collected at what cost?Access

What data is to be provided to which users whenappropriate?

Logical structure

How is data going to be arranged so that it makessense to a given user?

Physical organization

Where is the data going to be physically located?


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Types of Database Design An abstract model of how the database should bestructured and arranged to meet an organizationsinformation needs

Physical designA model of how the data will be organized andlocated within the database


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Data Modeling and Entity-RelationshipDiagrams

Data modelA map or diagram of entities and their relationships

Enterprise data modelingData modeling done at the level of the entireorganization.

Entity-Relationship (ER) Diagrams

Diagrams that use basic graphical diagrams to show theorganization of and relationships between data.Relationships include:

One-to-one (1:1), One-to-many (1:N), Many-to-many

(N:M)


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An Entity-Relationship Diagram


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Database Models

Hierarchical (tree) models Network modelsRelational models

Hierarchical Database Model A model in which the data is organized in a top-

down or inverted tree-like structure


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Hierarchical Database Model


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Network Models

An extension of the hierarchical model, in which amember may have many owners


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Relational Models

Data organized in tabular format (rows and columns) Relations: Two-dimensional tables into which data

elements are placed Tuple: Each row of a table Attributes: Columns of the table

Domain: Values for attributes or columns Compar ison of Database M odels


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Relational Models


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Data Manipulations

SelectingEliminating rows according to certain criteria.

ProjectingEliminating columns in a table.

Joining

Combining two or more tables.LinkingJoining tables that share at least one common dataelement.


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Creating and Modifying theDatabase Data definition language (DDL)

Collection of instructions and commands used todefine and describe data and data relationships in aspecific database

Data dictionary

A detailed description of all data used in thedatabase


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Data Dictionary

Provides a standard definition of terms and data elementsAssists programmers in designing and writing programsSimplifies database modificationsHelps achieve advantages of the database approachReduced data redundancyIncreased data reliability

Faster program developmentEasier modification of data and information


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Manipulating Data and GeneratingReports Structured Query Language (SQL)

A standardized data manipulation language thathas become an integral part of most relationaldatabase packages

Data Manipulation Language (DML)

Contains the commands used to manipulate the

databaseAllows managers and other database users toaccess, modify, and make queries about datacontained in the database to generate reports


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Selecting a Database ManagementSystem Begins by analyzing database needs andcharacteristics

PerformanceIntegrationFeaturesThe vendorCost


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Emerging Database Trends

Distributed databasesActual data may be spread across several smallerdatabases connected via telecommunicationsdevices

Replicated databaseHolds a duplicate set of frequently used data


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Data Warehouse

A relational database management system designedspecifically to support management decision making


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Data Warehouse


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Aspects of Database Administration

Overall design and coordination of the databaseDevelopment and maintenance of schemas and sub-schemas

Development and maintenance of the data dictionaryImplementation of the DBMSSystem and user documentationUser support and trainingOverall operation of the DBMSTesting and maintaining the DBMSEstablishing emergency or failure-recovery procedures


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Database Use, Policies, and Security

What data should users have direct access to?Under what circumstances can data be transferredfrom a PC or small computer system to the large

mainframe system (uploading)?Under what circumstances can data be transferredfrom a mainframe system to PCs or smallcomputer system (downloading)?What procedures are needed to guarantee properdatabase use?


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Information Systems Principles Without data and the ability to process it, an organizationwould not be able to successfully complete most businessactivities. A database can help companies organizeincreased amounts of data to maximize this valuable

resource.Often, distinct yet related databases must be linked to

provide enterprise-wide databases to meet the needs of themodern organization.

Determining what is to be collected in the database andwho will have access to this data are importantconsiderations in organizing data in a database.


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Information Systems PrinciplesCont .

Distributed databases allow more users to gain direct accessto data stored at different user sites. Thus, controlling whoaccesses and changes data is sometimes difficult.Organizing data to support on-line transaction processing issignificantly different than organizing it to support effectivemanagement decision making. As a result, special forms ofdatabases and associated tools have been developed foreach need.

Having an effective database administrator is essential foran organization to receive the full benefits expected of adatabase while avoiding potential pitfalls.

Data and Information.ppt

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