SQL Server and SQL

StructuredQueryLanguage

Hans-PetterHalvorsen

SQLServerandSQL

StepbystepExercises

DatabaseSystems

Hans-PetterHalvorsen,M.Sc.

DatabaseSystems

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ADatabaseisastructuredwaytostorelotsofinformation.Theinformationisstoredindifferenttables.- “Everything”todayisstoredindatabases!

Examples:• Bank/Accountsystems• InformationinWebpagessuchasFacebook,Wikipedia,YouTube,etc.

• Fronter,TimeEdit,etc.• …lotsofotherexamples!

DatabaseManagementSystems(DBMS)• MicrosoftSQLServer

– Enterprise,Developerversions,etc.(Professionaluse)– Expressversionisfreeofcharge

• Oracle• MySQL (ownedbyOracle,butpreviouslyownedbySun

Microsystems)- MySQLcanbeusedfreeofcharge(opensourcelicense),WebsitesthatuseMySQL:YouTube,Wikipedia,Facebook

• MicrosoftAccess• IBMDB2• Sybase• etc.

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WewilluseSQLserverbecauseitisverypopularintheindustrytoday,andwecanuseitforfreeviatheMicrosoftDreamSparkPremiumSubscription – whichisavailableforthestudentsandstaffatTelemarkUniversityCollege,orusetheExpressversionwhichisavailableforfreeforeverybody.

MicrosoftSQLServer

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SQLServerconsistsofaDatabaseEngineandaManagementStudio.TheDatabaseEnginehasnographicalinterface- itisjustaservicerunninginthebackgroundofyourcomputer(preferableontheserver).TheManagementStudioisgraphicaltoolforconfiguringandviewingtheinformationinthedatabase.Itcanbeinstalledontheserverorontheclient(orboth).

ThenewestversionofMicrosoftSQLServeris“SQLServer2014”

DatabaseDesign

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DatabaseDesign– ERDiagram

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ERDiagram(Entity-RelationshipDiagram)• UsedforDesignandModelingofDatabases.• SpecifyTablesandrelationship betweenthem(PrimaryKeysandForeignKeys)

PrimaryKeyPrimaryKey

ForeignKey

TableName

TableName

RelationalDatabase.InarelationaldatabaseallthetableshaveoneormorerelationwitheachotherusingPrimaryKeys(PK)andForeignKeys(FK).Note!YoucanonlyhaveonePKinatable,butyoumayhaveseveralFK’s.

ColumnNames

Example:

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PrimaryKeyPrimaryKey

ForeignKey

TableName

TableName

ColumnNames

Database- “BestPractice”

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• Tables:Useuppercaseandsingular formintablenames– notplural,e.g.,“STUDENT”(not“students”)

• Columns:UsePascalnotation,e.g.,“StudentId”• PrimaryKey:• Ifthetablenameis“COURSE”,namethePrimaryKeycolumn“CourseId”,etc.

• “Always”useInteger andIdentity(1,1) forPrimaryKeys.UseUNIQUEconstraintforothercolumnsthatneedstobeunique,e.g.“RoomNumber”

• SpecifyRequired Columns(NOTNULL)– i.e.,whichcolumnsthatneedtohavedataornot

• Standardizeonfew/theseDataTypes:int,float,varchar(x),datetime,bit

• UseEnglishfortableandcolumnnames• Avoidabbreviations!(Use“RoomNumber”– not“RoomNo”,“RoomNr”,...)

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Students:CreatethisExampleusingERwin.CreatetheTablesinSQLServer.

DatabaseDesignExercise

SQLServer


MicrosoftSQLServer– CreateaNewDatabase

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Nameyoudatabase,e.g.,WEATHER_SYSTEM

MicrosoftSQLServer

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WriteyourQueryhere

TheresultfromyourQuery

YourDatabase

YourTables

YourSQLServer

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MicrosoftSQLServer

Makesuretouncheckthisoption!

Doyougetanerrorwhentryingtochangeyourtables?

CreateTablesusingtheDesignerToolsinSQLServer

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Evenifyoucando“everything”usingtheSQLlanguage,itissometimeseasiertodosomethinginthedesignertoolsintheManagementStudioinSQLServer.Insteadofcreatingascriptyoumayaswelleasilyusethedesignerforcreatingtables,constraints,insertingdata,etc.

Select“NewTable…”: Next,thetabledesignerpopsupwhereyoucanaddcolumns,datatypes,etc.

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Inthisdesignerwemayalsospecifyconstraints,suchasprimarykeys,unique,foreignkeys,etc.

CreateTableswiththe“DatabaseDiagram”

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YoumayselectexistingtablesorcreatenewTables

CreateNewTable

EnterColumns,selectDataTypes,PrimaryKeys,etc.

StructuredQueryLanguageSQL


WhatisSQL

• SQL– StructuredQueryLanguage• SQLisastandardlanguageforaccessingdatabases.

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SQL– StructuredQueryLanguage

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• insert into STUDENT (Name , Number, SchoolId)values ('John Smith', '100005', 1)

• select SchoolId, Name from SCHOOL

• select * from SCHOOL where SchoolId > 100

• update STUDENT set Name='John Wayne' where StudentId=2

• delete from STUDENT where SchoolId=3

QueryExamples:

Wehave4differentQueryTypes:INSERT,SELECT,UPDATEand DELETE

ImportantSQLCommands• SELECT- extractsdatafromadatabase• UPDATE- updatesdatainadatabase• DELETE- deletesdatafromadatabase• INSERTINTO- insertsnewdataintoadatabase• CREATEDATABASE- createsanewdatabase• ALTERDATABASE- modifiesadatabase• CREATETABLE- createsanewtable• ALTERTABLE- modifiesatable• DROPTABLE- deletesatable• CREATEINDEX- createsanindex(searchkey)• DROPINDEX- deletesanindex

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SQL

DDL DML

StructuredQueryLanguage(SQL)

DataDefinitionLanguage(DDL) DataManipulationLanguage(DML)

Create Drop

Rename Alter

CRUD

CREATETables DELETETables

RENAMETables ALTERTables

Create

Read

Update

Delete

INSERTINTO

SELECT

UPDATE

DELETE

CreateTablesusingSQL

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CREATE TABLE [SCHOOL](

SchoolId int IDENTITY(1, 1) NOT NULL PRIMARY KEY,

SchoolName varchar(50) NOT NULL UNIQUE,Description varchar(1000) NULL,Address varchar50) NULL,Phone varchar(50) NULL,PostCode varchar(50) NULL,PostAddress varchar(50) NULL,

) GO......

Example:

SQLQueries

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Students:CreatethefollowingTableandDatausingSQL

TableName:CUSTOMER

INSERT

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Example:INSERTINTOCustomers(CustomerName,ContactName,Address,City,PostalCode,Country)VALUES('Cardinal','TomB.Erichsen','Skagen21','Stavanger','4006','Norway');

SELECT

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Students:WriteandExecutethefollowingQueries.

SELECT*FROMCUSTOMER

SELECT*FROMCUSTOMERWHERECustomerID=1

SELECTCustomerName,CityFROMCUSTOMER

SELECTDISTINCTCityFROMCUSTOMER

SELECT*FROMCUSTOMERWHERECountry='Mexico'

SQLisNOTcasesensitive:selectisthesameasSELECT

SELECT*FROMCUSTOMERWHERECountry='Germany’ANDCity='Berlin'

SELECT*FROMCUSTOMERWHERECity='Berlin’ORCity='München'

SELECT*FROMCUSTOMERORDERBYCountry

SELECT*FROMCUSTOMERORDERBYCountryDESC

UPDATE

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UPDATECUSTOMERSETContactName='AlfredSchmidt',City='Hamburg'WHERECustomerName='AlfredsFutterkiste'

UpdateWarning!Becarefulwhenupdatingrecords.WhathappensifwehadomittedtheWHEREclause,intheexampleabove,likethis:

UPDATECUSTOMERSETContactName='AlfredSchmidt',City='Hamburg';

DELETE

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DELETEFROMCUSTOMERWHERECustomerName='AlfredsFutterkiste'ANDContactName='MariaAnders'

Itispossibletodeleteallrowsinatablewithoutdeletingthetable

DELETE*FROMCUSTOMER

SQLQueries

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Students:CreatetheTablesshownaboveusingSQL

Students:InsertsomeDataintotheTablesusingSQL

SELECT

29Students:GetalldatafromtheBOOKtableusingSQL

AdvancedSQLFeatures• Views:Viewsarevirtualtableforeasieraccesstodatastoredinmultipletables.

• StoredProcedures:AStoredProcedureisaprecompiledcollectionofSQLstatements.Inastoredprocedureyoucanuseifsentence,declarevariables,etc.

• Triggers:Adatabasetriggeriscodethatisautomaticallyexecutedinresponsetocertaineventsonaparticulartableinadatabase.

• Functions:WithSQLandSQLServeryoucanuselotsofbuilt-infunctionsoryoumaycreateyourownfunctions

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GetDatafrommultiple tablesinasingleQueryusingJoins

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selectSchoolName,CourseNamefromSCHOOLinnerjoinCOURSEonSCHOOL.SchoolId =COURSE.SchoolId

Example:

YoulinkPrimaryKeysandForeignKeystogether

Students:TrythisExample

CreatingViewsusingSQL

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IF EXISTS (SELECT nameFROM sysobjectsWHERE name = 'CourseData' AND type = 'V')

DROP VIEW CourseDataGO

CREATE VIEW CourseDataAS

SELECTSCHOOL.SchoolId, SCHOOL.SchoolName, COURSE.CourseId, COURSE.CourseName,COURSE.Description

FROMSCHOOL INNER JOIN COURSE ON SCHOOL.SchoolId = COURSE.SchoolIdGO

select * from CourseDataYoucanUsetheViewasanordinarytableinQueries:

AViewisa“virtual”tablethatcancontaindatafrommultipletables

InsidetheViewyoujointhedifferenttablestogetherusingtheJOIN operator

TheNameoftheView

CreateView:

UsingtheView:

Thispartisnotnecessary– butifyoumakeanychanges,youneedtodeletetheoldversionbeforeyoucanupdateit

Students:CreatethisViewandmakesureitworks

CreatingViewsusingtheEditor

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SavetheView

GraphicalInterfacewhereyoucanselectcolumnsyouneed

StoredProcedure

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IFEXISTS(SELECTnameFROMsysobjectsWHEREname ='StudentGrade'AND type='P')

DROPPROCEDUREStudentGradeOG

CREATEPROCEDUREStudentGrade@Studentvarchar(50),@Coursevarchar(10),@Gradevarchar(1)

AS

DECLARE@StudentId int,@CourseId int

selectStudentIdfromSTUDENTwhereStudentName =@Student

selectCourseId fromCOURSEwhereCourseName =@Course

insertintoGRADE(StudentId,CourseId,Grade)values (@StudentId,@CourseId,@Grade)GO

execute StudentGrade 'John Wayne', 'SCE2006', 'B'

AStoredProcedureislikeMethodinC#- itisapieceofcodewithSQLcommandsthatdoaspecifictask– andyoureuseit

InputArguments

Internal/LocalVariables

ProcedureName

SQLCode(the“body”oftheStoredProcedure)

Note!Eachvariablestartswith@

CreateStoredProcedure:

UsingtheStoredProcedure:

Thispartisnotnecessary– butifyoumakeanychanges,youneedtodeletetheoldversionbeforeyoucanupdateit

Students:CreatethisStoredProcedureandmakesureitworks

Trigger

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IF EXISTS (SELECT nameFROM sysobjectsWHERE name = 'CalcAvgGrade' AND type = 'TR')

DROP TRIGGER CalgAvgGradeGO

CREATE TRIGGER CalcAvgGrade ON GRADEFOR UPDATE, INSERT, DELETEAS

DECLARE@StudentId int,@AvgGrade float

select @StudentId = StudentId from INSERTED

select @AvgGrade = AVG(Grade) from GRADE where StudentId = @StudentId

update STUDENT set TotalGrade = @AvgGrade where StudentId = @StudentId

GO

ATriggerisexecutedwhenyouinsert,updateordeletedatainaTablespecifiedintheTrigger.

InsidetheTriggeryoucanuseordinarySQLstatements,createvariables,etc.

NameoftheTrigger

SpecifywhichTabletheTriggershallworkon

Internal/LocalVariables

SQLCode(The“body”oftheTrigger)

SpecifywhatkindofoperationstheTriggershallacton

Note!“INSERTED”isatemporarilytablecontainingthelatestinserteddata,anditisveryhandytouseinsideatrigger

CreatetheTrigger:Thispartisnotnecessary– butifyoumakeanychanges,youneedtodeletetheoldversionbeforeyoucanupdateit

Students:CreatethisTriggerandmakesureitworks

Quiz

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http://www.w3schools.com/quiztest/quiztest.asp?qtest=SQL

TestyourskillswiththisMultiplechoiceTest

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SQLTutorial

CreateTablesusingSQL

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if not exists (select * from dbo.sysobjects where id = object_id(N'[SCHOOL]') and OBJECTPROPERTY(id, N'IsUserTable') = 1)

CREATE TABLE [SCHOOL](

[SchoolId] [int] IDENTITY(1, 1) NOT NULL PRIMARY KEY,[SchoolName] [varchar](50) NOT NULL UNIQUE,[Description] [varchar](1000) NULL,[Address] [varchar](50) NULL,[Phone] [varchar](50) NULL,[PostCode] [varchar](50) NULL,[PostAddress] [varchar](50) NULL,

) GO......

Students:CreatethenecessaryTablesinSQLServer(eitherwithaSQLScriptorusetheDesignerToolsinSQLServer)

References• H.-P.Halvorsen.(2014).StructuredQueryLanguage.Available:

http://home.hit.no/~hansha/?tutorial=sql• NTNU.(2013).TDT4140Systemutvikling.Available:

http://www.ntnu.no/studier/emner/TDT4140• UiO.(2013).INF1050- Systemutvikling.Available:

http://www.uio.no/studier/emner/matnat/ifi/INF1050/• O.Widder.(2013).geek&poke.Available:http://geek-and-poke.com• B.Lund.(2013).Lunch.Available:http://www.lunchstriper.no,

http://www.dagbladet.no/tegneserie/lunch/• S.Adams.Dilbert.Available:http://dilbert.com

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UniversityCollegeofSoutheastNorwaywww.usn.no

E-mail:[email protected]:http://home.hit.no/~hansha/

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