Database Management Systems: Relational Databases & SQL · 1 Database Management Systems:...

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DatabaseManagementSystems:RelationalDatabases&SQLCaitlynWolfUWChemicalEngineering

March5th,2019

DataScienceMethodsforCleanEnergyResearch(DSMCER)

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Announcements

• Studentstand-upsarethisafternoon!

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Outline

• Introductiontodatabasemanagementsystems(DBMS’s)• WhataretheyandwhyshouldIcare?

• Datamodels• Hierarchical,Network,Relational,Entity-Relationship

• Databasekeys• Databasenormalization• SQL

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WhatisadatabasemanagementsystemorDBMS?

AdatabasemanagementsystemorDBMSallowsausertoefficientlybuild,access,modifyandupdateadatabaseofinformation.

DBMS

Database

data

User1

Application

User2

schema

storage

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Advantages(andDisadvantages)ofaDBMS

• Improveddataaccessandsharing

DBMS

Database

data

schema

storage

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• Improveddataaccessandsharing• Dataadministrationandsecurity

DBMS

Database

data

schema

storage

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• Improveddataaccessandsharing• Dataadministrationandsecurity• Dataintegrity(accuracyandconsistency)

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• Improveddataaccessandsharing• Dataadministrationandsecurity• Dataintegrity(accuracyandconsistency)• Physicalandlogicaldataindependence

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DatabaseLevelsofAbstraction

ExternalLevel

LogicalorConceptualLevel

Reference:http://jcsites.juniata.edu/faculty/rhodes/dbms/dbarch.htm

Application 1 Application 2 User1 User2

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ExternalLevel


LogicalDataIndependence



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ExternalLevel


PhysicalorInternalLevel




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ExternalLevel


DiskStorage





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ExternalLevel



DiskStorage

PhysicalDataIndependence




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ExternalLevel



DiskStorage

PhysicalDataIndependence


DBMS

OperatingSystem



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• Improveddataaccessandsharing• Dataadministrationandsecurity• Dataintegrity(accuracyandconsistency)• Physicalandlogicaldataindependence• Datalossprotection

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• Highcost

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• Highcost• Requiresadditionalmanagementandsecurity

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• Highcost• Requiresadditionalmanagementandsecurity• Morecomplexthangeneralfilesystems

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DataModels

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DataModels:Hierarchical

Additional Reading: Stonebraker, Michael, and Joey Hellerstein. "What goes around comes around." Readings in Database Systems 4 (2005): 1724-1735

• Simplelanguagetointeractwithandretrievedatafromthesystem

• Somelogicaldataindependenceisallowed

• Each“child”canonlyhaveone“parent”but“parents”canhavemultiplechildren.

• Leadstoredundantdatapronetoinconsistenciesupon updates

• Doesnotofferflexibility(e.g.instructorcannotexistiftheyarenotteachingacourse)

• Lacksphysicaldataindependence (i.e.changesinphysicalstoragewouldbreakapplications)

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DataModels:Network


• Moreflexiblethanahierarchicalmodel

• Limitsredundantdatabyallowingmany-manyrelationships

• Complextoworkthroughandretrievedatafrom

• Nophysicaldataindependence

• Nologicaldataindependence

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DataModels:Relational


• OffersphysicalANDlogicaldataindependence

• Flexibledesign

• Simplisticcomparedtothenetworkmodel

• Languageisdifficulttounderstand(relationalalgebra&calculus)

• Inefficientdataretrieval

Inthe1980’s, IBMhadthefinalsayinthedebatebetweenrelationalandnetworkmodels….relationalcameoutontop(seeadditionalreading).

ClassID Number Name Credits

1 ChemE 545 DSMCER 3

2 ChemE 546 SEDS 3

InstructorID Name Email

1 DaveBeck [email protected]

2 ChadCurtis [email protected]

ClassID InstructorID

1 1

1 2

2 1

2 2

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DataModels:Entity-Relationship(E/R– Diagrams)


• Missingalanguageforinteractionswiththesystem

• Overshadowedbyrelationalmodels

• Becamesuccessfulasaschemadesigntoolforrelationaldatabases

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DataModels:Entity-Relationship(E/R– Diagrams)



2 ChemE 546 SEDS 3





1 1

1 2

2 1

2 2

Schema:roadmapofdataorganizationinthedatabase.

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DatabaseKeys

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DatabaseKeys



2 ChemE 546 SEDS 3





1 1

1 2

2 1

2 2

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Super,Candidate,PrimaryandForeignKeys

• Akeyisusedtouniquelyidentifyarow,ortuple,ineachtablewithinadatabase.

• Keysareespeciallyimportantfordefiningrelationshipsbetweendata.



2 ChemE 546 SEDS 3





1 1

1 2

2 1

2 2

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• Asuperkey isanattribute,orsetofattributes,thatcandetermineallotherattributesinatuple.

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Whatarethesuperkeys?

EmployeeID SocialSecurityNo. Name

1 123-45-ABCD Caitlyn

2 123-45-DCBA Dave

3 123-54-BACD Torin

4 456-12-BCAD Chad

5 456-98-BCDA Ted

6 123-54-ABDC Dave

• EmployeeID• SocialSecurityNumber• EmployeeID,SocialSecurityNumber• EmployeeID,Name• SocialSecurityNumber,Name• EmployeeID,SocialSecurityNumber,Name

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• Acandidatekey,alsocalledaminimalsuperkey,isakeyinwhichallattributesarerequiredforuniquelyidentifyingthetupleandremainingakey.Thisdoesnothavetobeasingleattribute.

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Whatarethecandidatekeys?




2 123-45-DCBA Dave

3 123-54-BACD Torin

4 456-12-BCAD Chad

5 456-98-BCDA Ted

6 123-54-ABDC Dave

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Whatarethecandidatekeys?




2 123-45-DCBA Dave

3 123-54-BACD Torin

4 456-12-BCAD Chad

5 456-98-BCDA Ted

6 123-54-ABDC Dave

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• Acandidatekey,alsocalledaminimalsuperkey,isakeyinwhichallattributesofthekeyarerequiredforuniquelyidentifyingthetupleandremainingakey.Thisdoesnothavetobeasingleattribute.

• Aprimarykeyisonespecificcandidatekeychoseninthedatabasedesigntoserveastheuniqueidentifierforeachtuple.

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Whatistheprimarykey?




2 123-45-DCBA Dave

3 123-54-BACD Torin

4 456-12-BCAD Chad

5 456-98-BCDA Ted

6 123-54-ABDC Dave

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Whatistheprimarykey?




2 123-45-DCBA Dave

3 123-54-BACD Torin

4 456-12-BCAD Chad

5 456-98-BCDA Ted

6 123-54-ABDC Dave

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• Acandidatekey,alsocalledaminimalsuperkey,isakeyinwhichallattributesofthekeyarerequiredforuniquelyidentifyingthetupleandremainingakey.Thisdoesnothavetobeasingleattribute.

• Aprimarykeyisonespecificcandidatekeychoseninthedatabasedesigntoserveastheuniqueidentifierforeachtuple.

• Aforeignkey referencesaprimarykeyinanothertableandisusedtodefinerelationshipsbetweentuplesinseparatetables.

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Whataretheprimaryandforeignkeys?

DepartmentID DepartmentName FloorLocation

100 Sales 1

200 Marketing 2

300 Payroll 2

DepartmentID EmployeeID

100 2

100 5

300 6

200 1

200 6

300 4

300 3



2 123-45-DCBA Dave

3 123-54-BACD Torin

4 456-12-BCAD Chad

5 456-98-BCDA Ted

6 123-54-ABDC Dave

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100 Sales 1

200 Marketing 2

300 Payroll 2


100 2

100 5

300 6

200 1

200 6

300 4

300 3

Primarykeys



2 123-45-DCBA Dave

3 123-54-BACD Torin

4 456-12-BCAD Chad

5 456-98-BCDA Ted

6 123-54-ABDC Dave

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100 Sales 1

200 Marketing 2

300 Payroll 2


100 2

100 5

300 6

200 1

200 6

300 4

300 3

Primarykeys

ForeignkeysEmployeeID SocialSecurityNo. Name


2 123-45-DCBA Dave

3 123-54-BACD Torin

4 456-12-BCAD Chad

5 456-98-BCDA Ted

6 123-54-ABDC Dave

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In-classactivity:Findthesuperandcandidatekeys

ClassName ClassNumber Instructor Department

DataScienceMethodsforCleanEnergyResearch 545 DaveBeck Chem E

DataScienceMethodsforCleanEnergyResearch 545 DaveBeck MSE

MachineLearning 546 KevinJamieson CSE

ColloidalSystems 556 JohnBerg Chem E

PrinciplesofDataManagement 544 DanSuciu CSE

SEDS 546 DaveBeck Chem E

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ClassName ClassNumber Instructor Department

DataScienceMethodsforCleanEnergyResearch 545 DaveBeck Chem E

DataScienceMethodsforCleanEnergyResearch 545 DaveBeck MSE

MachineLearning 546 KevinJamieson CSE

ColloidalSystems 556 JohnBerg Chem E

PrinciplesofDataManagement 544 DanSuciu CSE

SEDS 546 DaveBeck Chem E

• ClassName,Department• ClassNumber,Department• ClassName,Instructor,Department• ClassName,ClassNumber,Department• ClassNumber,Instructor,Department• ClassName,ClassNumber,Instructor,Department

SuperkeysCandidatekeys

In-classactivity:Findthesuperandcandidatekeys

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Normalization

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DatabaseNormalization

• Normalizationhelpswithschemadesignbyprovidingasetofrulestolimitdataredundancyandsupportdataintegrity

• Rulesgetmorestrictasmoveforwardthrough:• 1st NormalForm• 2nd NormalForm• 3rd NormalForm• BoyceCoddNormalForm(BCNF)

• Formoreinformationbeyondwhatwewillcovertoday,checkoutthisreferenceguide:

• https://www.studytonight.com/dbms/database-normalization.php

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1st NormalForm

• Alltablesshouldbe2-dimensional,i.e.notmorethanonevalueineachcell.

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1st NormalForm


• Whatdoyouseeasaprobleminthisdatabase:

Airline FlightNumber Path Plane

Model Pilot Passenger PassengerCity

PassengerState

Alaska 36 SEAàMSP A Dave Caitlyn Seattle Washington

AmericanAirlines 36 SEAà

MSP B Chad Ted Portland Oregon

Alaska 7 MSPàJFK C Dave Ted,Torin Portland,

SanDiegoOregon,California

Alaska 3367 MSPàJFK C Dave Caitlyn,

TorinSeattle,SanDiego

Washington,California

AmericanAirlines 3367 JFKà

SEA D Chad Torin SanDiego California

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1st NormalForm


• Whatdoyouseeasaprobleminthisdatabase:

Multiplepassengersaregroupedtogetherincommoncells.



PassengerState











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1st NormalForm

Airline FlightNumber

Passenger PassengerCity

PassengerState

Alaska 36 Caitlyn Seattle Washington

AmericanAirlines

36 Ted Portland Oregon

Alaska 7 Ted Portland Oregon

Alaska 7 Torin SanDiego California


Alaska 3367 Torin SanDiego California

AmericanAirlines

3367 Torin SanDiego California


Path PlaneModel

Pilot

Alaska 36 SEAà MSP A Dave

AmericanAirlines

36 SEAà MSP B Chad

Alaska 7 MSPà JFK C Dave

Alaska 3367 MSPà JFK C Dave

AmericanAirlines

3367 JFKà SEA D Chad


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2nd NormalForm

• 1st normalformmustbemetandthereshouldbenopartialfunctionaldependencies.

• ABàCDE,AàE

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2nd NormalForm


• ABàCDE,AàE

Airline FlightNumber Path Pilot PlaneModel

Alaska 36 SEAàMSP Dave A

AmericanAirlines 36 SEAàMSP Chad B

Alaska 7 MSPà JFK Dave C


AmericanAirlines 3367 JFKà SEA Chad D

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2nd NormalForm


• ABàCDE,AàE

Airline,FlightNumberà Path,Pilot,PlaneModelAirlineà Pilot

Airline FlightNumber Path Pilot PlaneModel

Alaska 36 SEAàMSP Dave A

AmericanAirlines 36 SEAàMSP Chad B



AmericanAirlines 3367 JFKà SEA Chad D

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2nd NormalForm


• ABàCDE,AàE

Airline FlightNumber Path PlaneModel

Alaska 36 SEAàMSP A

AmericanAirlines 36 SEAàMSP B

Alaska 7 MSPà JFK C


AmericanAirlines 3367 JFKà SEA D

Airline Pilot

Alaska Dave

AmericanAirlines Chad

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2nd NormalForm


• ABàCDE,AàE

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2nd NormalForm


• ABàCDE,AàEAirline FlightNumber Passenger PassengerCity PassengerState


AmericanAirlines 36 Ted Portland Oregon


Alaska 7 Torin Seattle Washington



AmericanAirlines 3367 Torin Seattle Washington

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2nd NormalForm


• ABàCDE,AàEAirline FlightNumber Passenger PassengerCity PassengerState


AmericanAirlines 36 Ted Portland Oregon





AmericanAirlines 3367 Torin Seattle Washington

Airline,FlightNumber,Passengerà City,StatePassengerà City,State

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2nd NormalForm


• ABàCDE,AàE

Airline FlightNumber Passenger

Alaska 36 Caitlyn

AmericanAirlines 36 Ted

Alaska 7 Ted

Alaska 7 Torin

Alaska 3367 Caitlyn

Alaska 3367 Torin

AmericanAirlines 3367 Torin

Passenger PassengerCity PassengerState

Caitlyn Seattle Washington

Ted Portland Oregon

Torin Seattle Washington

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3rd NormalForm

• 2nd normalformmustbemetandthereshouldbenotransitivefunctionaldependencies.

• Aà B,Bà C

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3rd NormalForm


• Aà B,Bà C



Ted Portland Oregon


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3rd NormalForm


• Aà B,Bà C



Ted Portland Oregon


Passengerà CityCityà State

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3rd NormalForm


• Aà B,Bà C


Caitlyn Seattle

Ted Portland

Torin Seattle

PassengerCity PassengerState

Seattle Washington

Portland Oregon

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BoyceCoddNormalForm(BCNF)

• Mustmeet3rd normalform,andeveryfunctionaldependencymustbetrivialorrepresentasuperkey.

• ABà C,Cà B

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• ABà C,Cà B







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• ABà C,Cà B







Airline,FlightNumber,Pathà PlaneModelPlaneModelà Path

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• ABà C,Cà B

Airline FlightNumber Path

Alaska 36 SEAàMSP

AmericanAirlines 36 SEAàMSP

Alaska 7 MSPà JFK

Alaska 3367 MSPà JFK

AmericanAirlines 3367 JFKà SEA

Path PlaneModel

SEAàMSP A

SEAàMSP B

MSPà JFK C

JFKà SEA D

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Wherewestarted



PassengerState











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FinaldesigninBCNF


Alaska 36 SEAà MSP

AmericanAirlines 36 SEAà MSP

Alaska 7 MSPà JFK



Path PlaneModel

SEAà MSP A

SEAà MSP B

MSPà JFK C

JFKà SEA D


Caitlyn Seattle

Ted Portland

Torin Seattle


Seattle Washington

Portland Oregon

Airline FlightNumber Passenger

Alaska 36 Caitlyn

AmericanAirlines 36 Ted

Alaska 7 Ted

Alaska 7 Torin

Alaska 3367 Caitlyn

Alaska 3367 Torin

AmericanAirlines 3367 Torin

Airline Pilot

Alaska Dave

AmericanAirlines Chad

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SQL:StructuredQueryLanguage

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SQL:StructuredQueryLanguage

• SQLcannotonlyallowyoutoretrievespecificdatafromarelationaldatabase,itenablesyoutocreate,delete,and/orupdateinformationinthedatabase.

• Today,wewillfocusonthebasicstructureforretrievingspecificdatafromadatabase.

• ThesewillstartwiththekeywordSELECT

• Formoreinformation,andacomprehensiveSQLtutorial,checkoutthisreference:

• https://www.w3schools.com/sql/sql_intro.asp

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SELECT

• YouwillalwaysstartyourSQLquerieswiththefollowingstructure:

SELECTfeature1,feature2,feature3…FROMtable;

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SELECT


Alaska 36 SEAà MSP


Alaska 7 MSPà JFK



Flights

SELECTAirline,FlightNumberFROMFlights;

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SELECT


Alaska 36 SEAà MSP


Alaska 7 MSPà JFK



Flights

SELECTAirline,FlightNumberFROMFlights;


Alaska 36

AmericanAirlines 36

Alaska 7

Alaska 3367

AmericanAirlines 3367

Results

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SELECT


Alaska 36 SEAà MSP


Alaska 7 MSPà JFK



Flights

SELECT*FROMFlights;

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SELECT


Alaska 36 SEAà MSP


Alaska 7 MSPà JFK



Flights

SELECT*FROMFlights;

ResultsAirline FlightNumber Path

Alaska 36 SEAà MSP


Alaska 7 MSPà JFK



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SELECTDISTINCT


Alaska 36 SEAà MSP


Alaska 7 MSPà JFK



Flights

SELECTDISTINCTAirlineFROMFlights;

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SELECTDISTINCT


Alaska 36 SEAà MSP


Alaska 7 MSPà JFK



Flights

SELECTDISTINCTAirlineFROMFlights;

Airline

Alaska

AmericanAirlines

Results

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WHERE


Alaska 36 SEAà MSP


Alaska 7 MSPà JFK



Flights

SELECT*FROMFlightsWHEREAirline=‘Alaska’;

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WHERE


Alaska 36 SEAà MSP


Alaska 7 MSPà JFK



Flights

SELECT*FROMFlightsWHEREAirline=‘Alaska’;


Alaska 36 SEAà MSP

Alaska 7 MSPà JFK


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WHERE

• YoucanusemanydifferentoperatorswiththeWHEREkeywordtodeclareacondition:

• =• <>or!=• >• <• >=• <=

• YoucanalsostringtogethermanyconditionalstatementsusingAND,OR,NOT

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WHERE


Alaska 36 SEAà MSP


Alaska 7 MSPà JFK



Flights

SELECT*FROMFlightsWHEREAirline=‘Alaska’ANDPath=‘SEAàMSP’;


Alaska 36 SEAà MSP

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JOINS

Imagesource:https://commons.wikimedia.org/wiki/File:SQL_Joins.svg

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INNERJOIN

Results

SELECTPassengers.Passenger,Homes.PassengerStateFROMPassengersINNERJOINHomesONPassengers.PassengerCity=Homes.PassengerCity;


Caitlyn Seattle

Ted Portland

Torin Seattle

Chad NewYork


Seattle Washington

Portland Oregon

SanDiego California

PassengersHomes

Passenger PassengerState

Caitlyn Washington

Ted Oregon

Torin Washington

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LEFTJOIN

SELECTPassengers.Passenger,Homes.PassengerStateFROMPassengersLEFTJOINHomesONPassengers.PassengerCity=Homes.PassengerCity;


Caitlyn Seattle

Ted Portland

Torin Seattle

Chad NewYork


Seattle Washington

Portland Oregon

SanDiego California

PassengersHomes

ResultsPassenger PassengerState

Caitlyn Washington

Ted Oregon

Torin Washington

Chad NULL

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AggregateFunctions

• COUNT,MAX,MIN,SUM,AVGareavailabletoperformoperationsonyourdataset


Caitlyn Seattle

Ted Portland

Torin Seattle

Dave Seattle

Chad NewYork

Passengers

SELECTCOUNT(Passenger)FROMPassengersWHEREPassengerCity=‘Seattle’;

COUNT(Passenger)

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Results

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GROUPBY

• YoucanalsoaGROUPBYkeywordwithanaggregatefunction


Caitlyn Seattle

Ted Portland

Torin Seattle

Dave Seattle

Chad NewYork

Passengers

SELECTCOUNT(Passenger),PassengerCityFROMPassengersGROUPBYPassengerCity

COUNT(Passenger) PassengerCity

3 Seattle

1 Portland

1 NewYork

Results

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Aliases

• Youcangivecolumnsortablestemporarynamesusinganalias


Caitlyn Seattle

Ted Portland

Torin Seattle

Dave Seattle

Chad NewYork

Passengers

SELECTCOUNT(Passenger)asTotal,PassengerCityFROMPassengersGROUPBYPassengerCity

Total PassengerCity

3 Seattle

1 Portland

1 NewYork

Results

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NestingwithSELECT

• Youcanselectfromatablethatistheresultofanotherquery


Caitlyn Seattle

Ted Portland

Torin Seattle

Dave Seattle

Chad NewYork

Passengers


Total PassengerCity

3 Seattle

1 Portland

1 NewYork

Results

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NestingwithSELECT

• Youcanselectfromatablethatistheresultofanotherquery

SELECTMAX(Total),PassengerCityFROM(SELECTCOUNT(Passenger)asTotal,PassengerCityFROMPassengersGROUPBYPassengerCity);

Total PassengerCity

3 Seattle

Results


Caitlyn Seattle

Ted Portland

Torin Seattle

Dave Seattle

Chad NewYork

Passengers


Total PassengerCity

3 Seattle

1 Portland

1 NewYork

Results

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PracticewritingSQLqueries

ThereferenceIprovidedalsoincludesapracticerelationaldatabase:https://www.w3schools.com/sql/trysql.asp?filename=trysql_select_all

Trywritingeachofthequeriesbelowandwritedowntheanswers:1. Howmanycustomersarethereinthedatabase?2. Howmanydifferentfirstnamesarethereamongtheemployees?3. Howmanydifferentcountriesarethesupplierslocatedin?4. HowmanysuppliersarelocatedinFrance?5. Whatisthemostofoneproductitemthatwaseverpurchasedonasingle

order?6. Whichcountryhasthemostsuppliers?(Hint:exploreanestedquery)7. CreateatableofProductNameandCategoryName forproductswitha

pricelessthan50.

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PracticewritingSQLqueries

ThereferenceIprovidedalsoincludesapracticerelationaldatabase:https://www.w3schools.com/sql/trysql.asp?filename=trysql_select_all

Trywritingeachofthequeriesbelowandwritedowntheanswers:1. Howmanycustomersarethereinthedatabase?912. Howmanydifferentfirstnamesarethereamongtheemployees?103. Howmanydifferentcountriesarethesupplierslocatedin?174. HowmanysuppliersarelocatedinFrance?35. Whatisthemostofoneproductitemthatwaseverpurchasedonasingle

order?1206. Whichcountryhasthemostsuppliers?(Hint:exploreanestedquery) USA7. CreateatableofProductNameandCategoryName forproductswitha

pricelessthan50.70rows

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