CSCI-UA: Database Design & Web Implementation. Professor Evan Sandhaus Lecture #7: Normalization

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1 CSCI-UA: Database Design & Web Implementation Professor Evan Sandhaus Lecture #7: Normalization Database Design and Web Implementation

2 Database Design and Web Implementation

3 Administrivia Readings: None for next class Homework: How s it going? Questions? Airline example to demonstrate what s expected. Database Design and Web Implementation 3

4 Airline Example Use cases Allow customers to book a flight. Allow customers to see the model of plane flown on a flight. Database Design and Web Implementation 4

5 Airline Example Use cases Allow customers to book a flight. Allow customers to see the model of plane flown on a flight. Database Design and Web Implementation 5

6 On Today s Menu Normalization 1st Normal Form 2nd Normal Form 3rd Normal Form Return To Spotify 2012 Election Results Example Database Design and Web Implementation 6

7 Assumptions Normalization assumes that it is preferable to minimize the amount of data stored, this is a point of view not an ironclad law of the universe. Database Design and Web Implementation 7

8 Normalization Database Design and Web Implementation 8

9 De-normalized data De-normalized data is data that can be more efficiently represented Symptoms Repeated data, Multiple values per column Mixture of multiple entities in a single record Album Track Release Year Length Track Green Day American Idiot American Idiot Green Day American Idiot Boulevard Of Broken Dreams Green Day Dookie Basket Case Wizards from Kansas Reunion River Road Wizards from Kansas Reunion Orion Fun Some Nights We Are Young Database Design and Web Implementation 9

10 Update Anomalies With de-normalized data its possible to update some instances of an entity without updating all instances of that entity. Album Track Release Year Length Track Green Day American Idiot American Idiot Green Day American Idiot Boulevard Of Broken Dreams Green Day Dookie Basket Case Wizards from Kansas Reunion River Road Wizards from Kansas Reunion Orion Fun Some Nights We Are Young Database Design and Web Implementation 10

11 Update Anomalies With de-normalized data its possible to update some instances of an entity without updating all instances of that entity. Album Track Release Year Length Track Green Day American Idiot American Idiot Green Day 0.99 American Idiot Boulevard Of Broken Dreams Green Day Dookie Basket Case Wizards from Kansas Reunion River Road Wizards from Kansas Reunion Orion Fun Some Nights We Are Young Database Design and Web Implementation 11

12 Insert Anomalies With de-normalized data it may be necessary to insert empty values for components of a composite primary key. Album Track Release Year Length Track Green Day American Idiot American Idiot Green Day American Idiot Boulevard Of Broken Dreams Green Day Dookie Basket Case Wizards from Kansas Reunion River Road Wizards from Kansas Reunion Orion Fun Some Nights We Are Young Database Design and Web Implementation 12

13 Insert Anomalies With de-normalized data it may be necessary to insert empty values for components of a composite primary key. Album Track Release Year Length Track Green Day American Idiot American Idiot Green Day American Idiot Boulevard Of Broken Dreams Green Day Dookie Basket Case Green Day Uno [empty] 2012 Wizards from Kansas Reunion River Road Wizards from Kansas Reunion Orion Fun Some Nights We Are Young Database Design and Web Implementation 13

14 Delete Anomalies With de-normalized data is is possible to inadvertently delete important entities. Album Track Release Year Length Track Green Day American Idiot American Idiot Green Day American Idiot Boulevard Of Broken Dreams Green Day Dookie Basket Case Wizards from Kansas Reunion River Road Wizards from Kansas Reunion Orion Fun Some Nights We Are Young Database Design and Web Implementation 14

15 Delete Anomalies With de-normalized data is is possible to inadvertently delete important entities. Album Track Release Year Length Track Green Day American Idiot American Idiot Green Day American Idiot Boulevard Of Broken Dreams Green Day Dookie Basket Case Wizards from Kansas Reunion River Road Wizards from Kansas Reunion Orion Database Design and Web Implementation 15

16 Functional Dependency If knowing the value of a set of columns X uniquely determines the value of another set of columns Y then we can say that Y is functionally dependent on X, written Y X. Area Phone First Last Code Number Ronald Sandhaus Evan Sandhaus Tara Sandhaus Francis Sandhaus Database Design and Web Implementation 16

17 Functional Dependency In this example: [Area Code, Phone Number] [First Last] Area Phone First Last Code Number Ronald Sandhaus Evan Sandhaus Tara Sandhaus Francis Sandhaus Database Design and Web Implementation 17

18 Key - A NEW Definition Based On Functional Dependency The key fields functionally determines all of the other fields in a table. Area Phone First Last Code Number Ronald Sandhaus Evan Sandhaus Tara Sandhaus Francis Sandhaus Database Design and Web Implementation 18

19 Primary Key - A NEW Definition Based On Functional Dependency A Primary Key contains no subset of fields that is also a key. Area Phone Zip First Last Code Number Ronald Sandhaus Evan Sandhaus Tara Sandhaus Francis Sandhaus Database Design and Web Implementation 19

20 1st Normal Form A database is in 1st normal form if no column contains multiple values. Album Id Album Album Countries 1 American Idiot US, UK, AU 1 American Idiot US, UK, AU 2 Dookie US, UK 3 Reunion US 3 Reunion US 4 Some Nights US, NZ, FR Database Design and Web Implementation 20

21 1st Normal Form A database is in 1st normal form if no column contains multiple values. Album Id Album 1 American Idiot 1 American Idiot 2 Dookie 3 Reunion 3 Reunion 4 Some Nights Album Id Album FK Countries 1 US 1 UK 1 AU 1 US 1 UK 1 AU 2 US 2 UK 3 US 3 US 4 US 4 NZ 4 FR Database Design and Web Implementation 21

22 Primary Key? Album Release Year Track Length Track Green Day American Idio2004 American Idiot Green Day American Idio2004 Boulevard Of Broken Dream Green Day Dookie 1994 Basket Case Wizards from Kansas Reunion 2011 River Road Wizards from Kansas Reunion 2011 Orion Fun Some Nights 2012 We Are Young Database Design and Web Implementation 22

23 2nd Normal Form A database is in 2nd normal form if it contains no tables in which a column depends on just part of the primary key. Album Release Year Track Length Track Green Day American Idiot 2004 American Idiot Green Day American Idiot 2004 Boulevard Of Broken Dream Green Day Dookie 1994 Basket Case Wizards from Kansas Reunion 2011 River Road Wizards from Kansas Reunion 2011 Orion Fun Some Nights 2012 We Are Young Database Design and Web Implementation 23

24 Primary Key? Album Release Year Track Length Track Green Day American Idio2004 American Idiot Green Day American Idio2004 Boulevard Of Broken Dream Green Day Dookie 1994 Basket Case Wizards from Kansas Reunion 2011 River Road Wizards from Kansas Reunion 2011 Orion Fun Some Nights 2012 We Are Young Database Design and Web Implementation 24

25 2nd Normal Form Functional Dependencies [] [ ] [Album] [Release Year] [Track] [Length, ] Album Release Year Track Length Track Green Day American Idiot 2004 American Idiot Green Day American Idiot 2004 Boulevard Of Broken Dream Green Day Dookie 1994 Basket Case Wizards from Kansas Reunion 2011 River Road Wizards from Kansas Reunion 2011 Orion Fun Some Nights 2012 We Are Young Database Design and Web Implementation 25

26 Second Normal Form Green Day Wizards from Kansas Fun Album American Idiot Dookie Reunion Some Nights FK Green Day Green Day Wizards From Kansas Fun Track Album FK Release Year Length Track American Idiot American Idiot Boulevard Of Broken DreamAmerican Idiot Basket Case Dookie River Road Reunion Orion Reunion We Are Young Some Nights Database Design and Web Implementation 26

27 3rd Normal Form A database is in 3rd normal form if it contains no table in which a column depends on another non-key column Track Album FK Release Year Length Track American Idiot American Idiot Boulevard Of Broken DreamAmerican Idiot Basket Case Dookie River Road Reunion Orion Reunion We Are Young Some Nights Database Design and Web Implementation 27

28 3rd Normal Form A database is in 3rd normal form if it contains no table in which a column depends on another non-key column Track Album FK Release Year Length Track American Idiot American Idiot Boulevard Of Broken DreamAmerican Idiot Basket Case Dookie River Road Reunion Orion Reunion We Are Young Some Nights Database Design and Web Implementation 28

29 3rd Normal Form Green Day Wizards from Kansas Fun Album Release Year FK American Idiot 2004 Green Day Dookie 1994 Green Day Reunion 2011 Wizards From Kansas Some Nights 2012 Fun Track Album FK Length Track American Idiot American Idiot Boulevard Of Broken DreamAmerican Idiot Basket Case Dookie River Road Reunion Orion Reunion We Are Young Some Nights Database Design and Web Implementation 29

30 Election Normalization ElectionDate State County Name Race Office Office Name Candidate Party First Last Incumbent Vote Postal Number ID Number Name Name Count Nov 6, 2012 AZ Arizona 4021 S U.S. Senate 8790 Dem Richard Carmona Nov 6, 2012 AZ Arizona 4021 S U.S. Senate 8789 GOP Jeff Flake Nov 6, 2012 AZ Arizona 4021 S U.S. Senate 9005 Lib Marc Victor Nov 6, 2012 CA California 8619 S U.S. Senate Dem Dianne Feinstein Nov 6, 2012 AZ Arizona 4021 S U.S. Senate GOP Elizabeth Emken Nov 6, 2012 MA Massachusetts S U.S. Senate Dem Elizabeth Warren Nov 6, 2012 AZ Arizona 4021 S U.S. Senate GOP Scott Brown A database is in 2nd normal form if it contains no tables in which a column depends on just part of the primary key. Database Design and Web Implementation 30

31 Election Normalization ElectionDate State Postal County Name Race Number Office Office Name ID Nov 6, 2012 AZ Arizona 4021 S U.S. Senate Nov 6, 2012 CA California 8619 S U.S. Senate Nov 6, 2012 MA Massachusetts S U.S. Senate Candidate Number Party First Name Last Name Incumbent Vote Count 8790 Dem Richard Carmona GOP Jeff Flake Lib Marc Victor Dem Dianne Feinstein GOP Elizabeth Emken Dem Elizabeth Warren GOP Scott Brown A database is in 3rd normal form if it contains no table in which a column depends on another non-key column Database Design and Web Implementation 31

32 Relating - Implementation Database Design and Web Implementation 32

33 Relating Implementation Database Design and Web Implementation 33

34 Relating - Implementation Database Design and Web Implementation 34

35 Use Case Spotify Find all of the albums for an artist Find all of the track names, lengths, and popularity on an album. Display an album s title, popularity, release year and cover art. Display the last n tracks a user has listened to Allow users to create playlists of tracks Database Design and Web Implementation 35