Chapter 12: Information Systems Chapter 12 Information Systems Page 127 Information systems are software applications that facilitate the organization

Chapter 12: Information Chapter 12: Information SystemsSystems

Chapter 12Chapter 12Information Information

SystemsSystemsPage Page 11

Information systems are Information systems are software applications software applications that facilitate the that facilitate the organization and analysis organization and analysis of data.of data.Example: Spreadsheet Example: Spreadsheet software allows users to software allows users to place raw data in tables and place raw data in tables and then utilize formulas and then utilize formulas and basic graphical mechanisms basic graphical mechanisms to generate calculations and to generate calculations and illustrations from it.illustrations from it.

Database StructuresDatabase Structures



An alternative to a distributed information An alternative to a distributed information system based upon files is a centralized system based upon files is a centralized system based upon the concept of system based upon the concept of databasesdatabases..

File-OrientedFile-OrientedSystemSystem

Database-Database-OrientedOrientedSystemSystem

Video Video Rental Rental FilesFiles

RentRental al

DeptDept..

VideoVideoSalesSalesFilesFiles

SaleSales s

DeptDept..

Video Video PurchaPurcha

se se FilesFiles

PurcPurch-h-

asinasing g

DeptDept..

AdvertAdvertise-ise-

mentmentFilesFiles

MarkeMarket-ing t-ing Dept.Dept.

Store Store UpkeeUpkeep Filesp Files

MainMaint-t-

enanenance ce

DeptDept..

Store Store PersonPerson

nel nel FilesFiles

PayrPayroll oll

DeptDept..

RentaRental l

Dept.Dept.

Sales Sales Dept.Dept. PurchPurch

--asing asing Dept.Dept.

MarketMarket-ing -ing

Dept.Dept.

IntegrateIntegrated d

DatabaseDatabase

MaintMaint--

enancenance e

Dept.Dept.

PayroPayroll ll

Dept.Dept.DISADVANTAGES OF EACH DISADVANTAGES OF EACH SYSTEMSYSTEM

File-OrientedFile-Oriented Database-Database-OrientedOriented

Duplication of effortDuplication of effort Data security Data security problemsproblems

Multiple error sourcesMultiple error sources Widespread error Widespread error effectseffects

A Modular View of a Database A Modular View of a Database SystemSystem



The DBMS uses The DBMS uses schemaschema and and

subschemasubschema to to ensure data ensure data

security.security.

A schema A schema describes the describes the way the entire way the entire

database is database is organized.organized.

A subschema A subschema describes the describes the

organization of organization of the portion of the the portion of the database that is database that is accessible to a accessible to a

particular type of particular type of user.user.

The Relational Database ModelThe Relational Database Model



The simplest conceptual arrangement of a The simplest conceptual arrangement of a database uses a table of rows (called database uses a table of rows (called tuplestuples) ) and columns (called and columns (called attributesattributes).).Last Name

First Name

M.I.

SID Hrs

Class

GPA

Major

DOB Image

MooseBullwinkl

eJ

900626977

112

Sr3.24

CHEM

03/21/76

Bear Yogi D900129

87548 So

2.17

BIOL02/16/

79

Coyote Wile E900705

54854 So

3.16

MATH

11/05/81

HoundHucklebe

rryH

900339227

75 Jr3.05

MKTG

09/12/83

Gorilla Magilla B900187

014102

Sr3.76

ELED12/12/

80

Pig Porky P900882

63566 Jr

2.38

ECON

05/02/82

The major The major advantage of this advantage of this model is its logical model is its logical conceptualization.conceptualization.

The major disadvantage is the The major disadvantage is the substantial amount of software substantial amount of software

and hardware overhead required and hardware overhead required to maintain and access the table.to maintain and access the table.

Relational Operator SELECTRelational Operator SELECT



The SELECT operation determines which The SELECT operation determines which tuples have particular attributes.tuples have particular attributes.

ORIGINAL TABLEORIGINAL TABLE

CodeCode DescriptionDescription PricPricee

213342133455

9v Battery9v Battery 1.921.92

311453114522

Power DrillPower Drill 34.934.999

254462544677

60W Bulb60W Bulb 1.471.47

309773097722

Mini-Ratchet Mini-Ratchet SetSet

6.506.50

256562565688

Halogen Halogen LightLight

12.912.999

290032900311

Flat Flat ScrewdriverScrewdriver

8.458.45

NEW TABLENEW TABLE


213342133455


254462544677


309773097722


6.506.50

290032900311


8.458.45

Apply Apply SELECT SELECT

withwithPrice < Price < 10.0010.00

Relational Operator PROJECTRelational Operator PROJECT



The PROJECT operation limits the scope The PROJECT operation limits the scope of the database to specific attributes.of the database to specific attributes.

ORIGINAL TABLEORIGINAL TABLE


213342133455


311453114522

Power DrillPower Drill 34.934.999

254462544677


309773097722


6.506.50

256562565688

Halogen Halogen LightLight

12.912.999

290032900311


8.458.45

NEW NEW TABLETABLE

CodeCode PricPricee

213342133455

1.921.92

311453114522

34.934.999

254462544677

1.471.47

309773097722

6.506.50

256562565688

12.912.999

290032900311

8.458.45

Apply Apply PROJECT PROJECT

withwithCode & Code & PricePrice

Relational Operator JOINRelational Operator JOIN



The JOIN operation combines multiple The JOIN operation combines multiple tables that have common attributes.tables that have common attributes.

Table CUSTOMERTable CUSTOMER

CusNCusNoo

CusNaCusNameme

CusZCusZipip

RepNRepNoo

11324113244545

WalkerWalker 6244624499

231231

13212132124242

RodriguRodriguezez

6202620255

125125

16573165739999

VanlooVanloo 6236623633

231231

13122131224343

RakowsRakowskiki

6229622944

167167

15423154231111

SmithsoSmithsonn

6202620255

421421

12177121778282

AdaresAdares 6265626500

125125

NEW TABLENEW TABLE

CusNoCusNo CusNaCusNameme

CusZiCusZipp

RepNoRepNo RepPhonRepPhonee

11324113244545

WalkerWalker 6244962449 231231 61824311618243112424

13212132124242

RodriguRodriguezez

6202562025 125125 61824398618243988787

16573165739999

VanlooVanloo 6236362363 231231 61824311618243112424

13122131224343

RakowskRakowskii

6229462294 167167 61834267618342677878

12177121778282

AdaresAdares 6265062650 125125 61824398618243988787

Apply JOIN withApply JOIN withCUSTOMER.RepCUSTOMER.Rep

No = No = SALESREP.RepIDSALESREP.RepID

Table Table SALESREPSALESREP

RepID RepPhone

125 6182439887

167 6183426778

231 6182431124

333 3145267759

Concurrency ControlConcurrency Control



A potential problem with database A potential problem with database systems that allow multiple access points systems that allow multiple access points is the loss of data integrity.is the loss of data integrity.

At ATM #1: At ATM #1: Deposit $400Deposit $400

At ATM #2: At ATM #2: Withdraw $200Withdraw $200Get Balance... Get Balance...

$500$500Get Balance... Get Balance... $500$500Add $400 to Add $400 to

Balance... Balance... $900$900Subtract $200 from Subtract $200 from Balance... Balance... $300$300Store new Balance... Store new Balance...

$900$900Store new Balance... Store new Balance... $300$300

Either balance that’s stored would be Either balance that’s stored would be incorrect, since the correct balance is incorrect, since the correct balance is $700$700!!

Databases and PrivacyDatabases and Privacy



The proliferation of information on The proliferation of information on database systems poses a potential threat database systems poses a potential threat to the privacy of people about whom the to the privacy of people about whom the data refers.data refers.

Example: Medical DatabasesExample: Medical Databases

Advantages:Advantages:•Reduction of paperworkReduction of paperwork•Fewer false insurance Fewer false insurance claimsclaims•Facilitates disease Facilitates disease trackingtracking•Immediate access in Immediate access in emergencyemergency•Cost-effective ID of Cost-effective ID of treatmenttreatment•Safer than paper Safer than paper recordsrecords

Disadvantages:Disadvantages:•Employer access might Employer access might cost jobscost jobs•““High risk” insurance High risk” insurance increasesincreases•Unsolicited Unsolicited advertisementsadvertisements•Fear inhibits candid Fear inhibits candid disclosuredisclosure•Inaccuracies are spread Inaccuracies are spread easilyeasily•Dr./patient Dr./patient confidentiality lossconfidentiality loss

CryptographyCryptography



Networks are set up to send messages Networks are set up to send messages right past stations that aren’t right past stations that aren’t authorized to read them, but what’s to authorized to read them, but what’s to preventprevent such unauthorized viewing? such unauthorized viewing?

The most common solution to this The most common solution to this problem is problem is encryptionencryption, where the , where the message is coded in such a way that message is coded in such a way that only the receiving station can decode only the receiving station can decode it.it.

Message

Message

Public-Key EncryptionPublic-Key Encryption



1.1.Create Create

MessageMessage

I have affixed I have affixed to me the dirt to me the dirt and dust of and dust of countless countless ages!ages!

ChuckChuck mdbriugndlwgmdbriugndlwgLinusLinus mamnsgfyddkdmamnsgfyddkdLucyLucy qhgwdnchsgshqhgwdnchsgshPattyPatty ahwbsgcydhzxahwbsgcydhzx

2.2.Look Up Look Up

Recipient’Recipient’s Public s Public

KeyKey

3.3.Encrypt Encrypt

Message With Message With Recipient’s Recipient’s Public KeyPublic Key

xsjb2dhdkWb$xsjb2dhdkWb$xzduYdm!xzduYdm!dj5slLssghd8ndj5slLssghd8nd&hsnqabi?d&hsnqabi?dsjsg%dsjsg%

4.4.Transmit Transmit Encrypted Encrypted MessageMessage

xsjb2dhdkWb$xsjb2dhdkWb$xzduYdm!xzduYdm!dj5slLssghd8ndj5slLssghd8nd&hsnqabi?d&hsnqabi?dsjsg%dsjsg%

5.5.Decrypt Message Decrypt Message With Recipient’s With Recipient’s

Private KeyPrivate Key

I have affixed I have affixed to me the dirt to me the dirt and dust of and dust of countless countless ages!ages!

Key-Based AuthenticationKey-Based Authentication



When a message is received, how can you be sure When a message is received, how can you be sure who it came from?who it came from?

1.1.Create Create

MessageMessage

I’m going to recruit I’m going to recruit that funny-looking kid that funny-looking kid who plays shortstop who plays shortstop on Chuck’s team!on Chuck’s team!

2.2.Encrypt Message Encrypt Message

With Sender’s With Sender’s Private KeyPrivate Key

Ma3ndhvyr#bcjaqwMa3ndhvyr#bcjaqwpfQkguiorkfohskxi8pfQkguiorkfohskxi8vcevce%fpgkjfhikfvdamxx%fpgkjfhikfvdamxxyemfideychssfhsgdyemfideychssfhsgdhahdm$dlglyn7buchahdm$dlglyn7buchsohso

3.3.Transmit Transmit Encrypted Encrypted MessageMessage

Ma3ndhvyr#bcjaqwMa3ndhvyr#bcjaqwpfQkguiorkfohskxi8pfQkguiorkfohskxi8vcevce%fpgkjfhikfvdamxx%fpgkjfhikfvdamxxyemfideychssfhsgdyemfideychssfhsgdhahdm$dlglyn7buchahdm$dlglyn7buchsohso

4.4.Decrypt Message Decrypt Message

With Sender’s With Sender’s Public KeyPublic Key

I’m going to recruit I’m going to recruit that funny-looking kid that funny-looking kid who plays shortstop who plays shortstop on Chuck’s team!on Chuck’s team!

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Chapter 12: Information Systems Chapter 12 Information Systems Page 127 Information systems are software applications that facilitate the organization