![Page 1: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/1.jpg)
CS639:DataManagementfor
DataScienceLecture3:PrinciplesofDataManagement
TheodorosRekatsinas1
![Page 2: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/2.jpg)
2
Announcements• Mix-upwithduedatesL Itshouldbefixednow.• Nochangestothemidterm
• UpdatesandhintsonPA1assignmentonPiazza
• Questions?
![Page 3: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/3.jpg)
Today’sLecture
1. DataManagement
2. DataModels
3. RDBMsandtheRelationalDataModel
3
![Page 4: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/4.jpg)
1.DataManagement
4
Section1
![Page 5: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/5.jpg)
• Datarepresentsthetraces ofreal-worldprocesses.
• Dataisvaluablebuthardandcostlytomanage• Storage,representationcomplexity,collection
• Datamanagementseekstoanswertwoquestions:• Whatoperationsdowewanttoperformonthisdata?• Whatfunctionalitydoweneedtomanagethisdata?
5
Section1
DataManagement
![Page 6: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/6.jpg)
• Describereal-worldentitiesintermsofstoreddata• Create&persistentlystorelargedatasets• Efficientlyquery&update• Musthandlecomplexquestionsaboutthedata• Musthandlesophisticatedupdates• Performancematters
• Changestructure(e.g.,addattributes)• Concurrencycontrol:enablesimultaneousqueries,updatesetc• Crashrecovery• Accesscontrol,security,integrity
6
Section1
RequiredFunctionality
Itisdifficultandcostlytoimplementallthesefeatures!
![Page 7: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/7.jpg)
• Relationaldatabasemanagementsystems• HDFS-basedsystems(e.g.,hadoop)• Streammanagementsystems:ApacheKafka• Others?
7
Section1
Systemsprovidingdatamanagementfeatures
![Page 8: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/8.jpg)
8
Section1
![Page 9: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/9.jpg)
2.DataModels
9
Section2
![Page 10: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/10.jpg)
Whatyouwilllearnaboutinthissection
1. TypesofData
2. DataModels
10
Section2
![Page 11: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/11.jpg)
• Structureddata
• Semi-structureddata
• Unstructureddata
11
Section2
Dataishighlyheterogeneous
Increasingamountsofdata
![Page 12: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/12.jpg)
• Informationwithahighdegreeoforganization
• Alldataconformstoaschema.Ex:businessdata
• Easytoquery,searchover,aggregate
• Example:tablesinadatabase,tablesinexcel,etc.
12
Section2
Structureddata
![Page 13: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/13.jpg)
• Somestructureinthedatabutimplicitandirregular
• Itcontains tagsorothermarkerstoseparatesemanticelementsandenforcehierarchiesofrecordsandfieldswithinthedata
• Example:JSON,HTML,XML
13
Section2
Semi-structureddata
![Page 14: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/14.jpg)
• Informationthateitherdoesnothaveapre-defined structure orisnotorganizedinapre-definedmanner.
• Text,video,images,etc.
• Abundantandextremelyvaluable.Hardtoquery,aggregate,analyze,search.
14
Section2
Unstructureddata
![Page 15: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/15.jpg)
• Adatamodelisacollectionofconceptsfordescribingdata
• Aschema isadescriptionofaparticularcollectionofdata,usingthegivendatamodel
• Adatamodel enablesuserstodefinethedatausinghigh-levelconstructswithoutworryingaboutmanylow-leveldetailsofhowdatawillbestoredondisk.
15
Section2
DataModel
![Page 16: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/16.jpg)
16
Section2
Levelsofabstraction
![Page 17: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/17.jpg)
17
Section2
Datamodels
• Relational• Key/Value• Graph• Document• Column-family• Array/Matrix• Hierarchical• Network
Mostdatabasemanagementsystems
![Page 18: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/18.jpg)
• Relational• Key/Value• Graph• Document• Column-family• Array/Matrix• Hierarchical• Network
18
Section2
Datamodels
NoSQL
![Page 19: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/19.jpg)
• Relational• Key/Value• Graph• Document• Column-family• Array/Matrix• Hierarchical• Network
19
Section2
Datamodels
Machinelearning,Scientificapplications
![Page 20: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/20.jpg)
• Relational• Key/Value• Graph• Document• Column-family• Array/Matrix• Hierarchical• Network
20
Section2
Datamodels
Obsolete/Rare
![Page 21: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/21.jpg)
3.RDBMsandtheRelationalDataModel
21
Section3
![Page 22: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/22.jpg)
Whatyouwilllearnaboutinthissection
1. DefinitionofDBMS
2. Datamodels&therelationaldatamodel
3. Schemas&dataindependence
22
Section3
![Page 23: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/23.jpg)
WhatisaDBMS?
• Alarge,integratedcollectionofdata
• Modelsareal-worldenterprise• Entities(e.g.,Students,Courses)• Relationships(e.g., AliceisenrolledinCS564)
ADatabaseManagementSystem(DBMS) isapieceofsoftwaredesignedtostoreandmanagedatabases
23
Section3
![Page 24: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/24.jpg)
24
AMotivating,RunningExample
• Considerbuildingacoursemanagementsystem(CMS):
• Students• Courses• Professors
• Whotakeswhat• Whoteacheswhat
Entities
Relationships
Section3
![Page 25: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/25.jpg)
Datamodels• Adatamodelisacollectionofconceptsfordescribingdata
• Therelationalmodelofdata isthemostwidelyusedmodeltoday• MainConcept:therelation- essentially,atable
• Aschema isadescriptionofaparticularcollectionofdata,usingthegivendatamodel
• E.g.everyrelation inarelationaldatamodelhasaschema describingtypes,etc.
25
Section3
![Page 26: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/26.jpg)
ModelingtheCourseManagementSystem• LogicalSchema• Students(sid:string,name:string,gpa:float)• Courses(cid:string,cname:string,credits:int)• Enrolled(sid:string,cid:string,grade:string)
sid Name Gpa101 Bob 3.2123 Mary 3.8
Students
cid cname credits564 564-2 4308 417 2
Coursessid cid Grade123 564 A
Enrolled
Relations
26
Section3
![Page 27: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/27.jpg)
ModelingtheCourseManagementSystem• LogicalSchema• Students(sid:string,name:string,gpa:float)• Courses(cid:string,cname:string,credits:int)• Enrolled(sid:string,cid:string,grade:string)
sid Name Gpa101 Bob 3.2123 Mary 3.8
Students
cid cname credits564 564-2 4308 417 2
Coursessid cid Grade123 564 A
Enrolled27
Correspondingkeys
Section3
![Page 28: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/28.jpg)
OtherSchemata…
• PhysicalSchema:describesdatalayout• Relationsasunorderedfiles• Somedatainsortedorder(index)
• LogicalSchema:Previousslide
• ExternalSchema:(Views)• Course_info(cid:string,enrollment:integer)• Derivedfromothertables
Applications
Administrators
28
Section3
![Page 29: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/29.jpg)
DataindependenceConcept: Applicationsdonotneedtoworryabouthowthedataisstructuredandstored
Logicaldataindependence:protectionfromchangesinthelogicalstructureofthedata
Physicaldataindependence:protectionfromphysicallayoutchanges
OneofthemostimportantreasonstouseaDBMS 29
I.e.shouldnotneedtoask:canweaddanewentityorattributewithoutrewritingtheapplication?
I.e.shouldnotneedtoask:whichdisksarethedatastoredon?Isthedataindexed?
Section3
![Page 30: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/30.jpg)
• Structure:Thedefinitionofrelationsandtheircontents.
• Integrity:Ensurethedatabase’scontentssatisfyconstraints.
• Manipulation:Howtoaccessandmodifyadatabase’scontents.
RelationalModel
30
Section3
![Page 31: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/31.jpg)
31
TablesintheRelationalModel
PName Price Manufacturer
Gizmo $19.99 GizmoWorks
Powergizmo $29.99 GizmoWorks
SingleTouch $149.99 Canon
MultiTouch $203.99 Hitachi
ProductArelation ortable isamultiset oftupleshavingtheattributesspecifiedbytheschema
Let’sbreakthisdefinitiondown
Section3
![Page 32: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/32.jpg)
32
TablesintheRelationalModel
PName Price Manufacturer
Gizmo $19.99 GizmoWorks
Powergizmo $29.99 GizmoWorks
SingleTouch $149.99 Canon
MultiTouch $203.99 Hitachi
Product
Amultiset isanunorderedlist(or:asetwithmultipleduplicateinstancesallowed)
List:[1,1,2,3]Set:{1,2,3}Multiset:{1,1,2,3}
i.e.nonext(),etc.methods!
Section3
![Page 33: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/33.jpg)
33
TablesintheRelationalModel
PName Price Manufacturer
Gizmo $19.99 GizmoWorks
Powergizmo $29.99 GizmoWorks
SingleTouch $149.99 Canon
MultiTouch $203.99 Hitachi
Product Anattribute (orcolumn)isatypeddataentrypresentineachtupleintherelation
Attributesmusthaveanatomictype,i.e.notalist,set,etc.
Section3
![Page 34: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/34.jpg)
34
TablesintheRelationalModel
PName Price Manufacturer
Gizmo $19.99 GizmoWorks
Powergizmo $29.99 GizmoWorks
SingleTouch $149.99 Canon
MultiTouch $203.99 Hitachi
Product
Atuple orrow isasingleentryinthetablehavingtheattributesspecifiedbytheschemaAlsoreferredtosometimesasarecord
Section3
![Page 35: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/35.jpg)
35
TablesintheRelationalModel
PName Price Manufacturer
Gizmo $19.99 GizmoWorks
Powergizmo $29.99 GizmoWorks
SingleTouch $149.99 Canon
MultiTouch $203.99 Hitachi
Product
Thenumberoftuplesisthecardinality oftherelation
Thenumberofattributesisthearity oftherelation
Section3
n-ary Relation=
Table with n columns
![Page 36: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/36.jpg)
36
DataTypesinRelationalModel
• Atomictypes:• Characters:CHAR(20),VARCHAR(50)• Numbers:INT,BIGINT,SMALLINT,FLOAT• Others:MONEY,DATETIME,…
• Everyattributemusthaveanatomictype• Hencetablesareflat
Section3
![Page 37: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/37.jpg)
37
TableSchemas
• Theschema ofatableisthetablename,itsattributes,andtheirtypes:
• Akey isanattributewhosevaluesareunique;weunderlineakey
Product(Pname: string, Price: float, Category: string, Manufacturer: string)
Product(Pname: string, Price: float, Category: string, Manufacturer: string)
Section3
![Page 38: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/38.jpg)
Keyconstraints
• Akeyisanimplicitconstraintonwhichtuplescanbeintherelation
• i.e.iftwotuplesagreeonthevaluesofthekey,thentheymustbethesametuple!
1.Whichwouldyouselectasakey?2.Isakeyalwaysguaranteedtoexist?3.Canwehavemorethanonekey?
Akey isaminimalsubsetofattributes thatactsasauniqueidentifierfortuplesinarelation
Students(sid:string, name:string, gpa: float)
Section3
![Page 39: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/39.jpg)
NULLandNOTNULL
• Tosay“don’tknowthevalue”weuseNULL• NULLhas(sometimespainful)semantics,moredetailslater
sid name gpa123 Bob 3.9143 Jim NULL Say,Jimjustenrolledinhisfirstclass.
WemayconstrainacolumntobeNOTNULL,e.g.,“name”inthistable
Students(sid:string, name:string, gpa: float)
Section3
![Page 40: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/40.jpg)
ForeignKeyconstraints
• Aforeignkey specifiesthatanattributefromonerelationhastomaptoatupleinanotherrelation.
Section3
![Page 41: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/41.jpg)
ForeignKeyconstraints
student_id aloneisnotakey- whatis?
sid name gpa101 Bob 3.2123 Mary 3.8
student_id cid grade
123 564 A123 537 A+
Students Enrolled
Wesaythatstudent_id isaforeignkey thatreferstoStudents
Students(sid: string, name: string, gpa: float)
Enrolled(student_id: string, cid: string, grade: string)
• Supposewehavethefollowingschema:
• Andwewanttoimposethefollowingconstraint:• ‘Onlyrealstudentsmayenrollincourses’ i.e.astudentmustappearintheStudentstabletoenrollinaclass
Section3
![Page 42: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/42.jpg)
SummaryofSchemaInformation
• SchemaandConstraintsarehowdatabasesunderstandthesemantics(meaning)ofdata
• Theyarealsousefulforoptimization
Section3
![Page 43: Lecture 3 PDM - GitHub Pages · Modeling the Course Management System •Logical Schema •Students(sid: string, name: string, gpa: float) •Courses(cid: string, cname: string, credits:](https://reader034.vdocument.in/reader034/viewer/2022042220/5ec5e5ad8570db7987671859/html5/thumbnails/43.jpg)
DATAMANIPULATIONLANGUAGES(DML)
• Howtostoreandretrieveinformationfromadatabase.
• Procedural:Thequeryspecifiesthe(high-level)strategytheDBMSshouldusetofindthedesiredresult.
• WewillseeSQLandRelationalAlgebra
Section3