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IntroductiontoERwin DatabaseDesign&Modelling withStepbystepExercises Hans-PetterHalvorsen,M.Sc. DatabaseDesign– ERDiagram ERDiagram(Entity-RelationshipDiagram) • UsedforDesignandModelingofDatabases. • SpecifyTablesandrelationship betweenthem(PrimaryKeysandForeignKeys) TableName Example: TableName Column Names PrimaryKey PrimaryKey ForeignKey RelationalDatabase.InarelationaldatabaseallthetableshaveoneormorerelationwitheachotherusingPrimaryKeys(PK)and ForeignKeys(FK).Note!YoucanonlyhaveonePKinatable,butyoumayhaveseveralFK’s. Database- “BestPractice” • 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.UseUNIQUE constraintforothercolumnsthatneedstobeunique,e.g.“RoomNumber” • SpecifyRequired Columns(NOTNULL)– i.e.,whichcolumnsthatneedtohave dataornot • Standardizeonfew/theseDataTypes:int,float,varchar(x),datetime,bit • UseEnglishfortableandcolumnnames • Avoidabbreviations!(Use“RoomNumber”– not“RoomNo”,“RoomNr”,...) DatabaseDesign&Implementation RecommendedSteps: 1. DatabaseModelling/DesignusingERwin 2. GenerateSQLTableScriptusingERwin(youmight needtoadjust/improveitinordertomakeitmore robust) 3. GenerateTablesinSQLServerusingtheSQLScript generatedbyERwin 4. CreateStoredProcedures,View,Triggers,etc.if needed. CAERwinDataModelerCommunityEdition • ToolforDatabaseModelling(ERDiagrams) • Free! • ForwardandReverseEngineeringwitha25object limit Downloadhere: http://erwin.com/products/data-modeler/community-edition ERwinExample IntroductiontoERwin OpenERwinandselectFile->New... Thefollowing windowappears(NewModel): Makesuretoselect Logical/Physical Model SelecttheDatabaseTypeandVersion youshalluse IntroductiontoERwin IntroductiontoERwin Students:LettrytocreatethefollowingTables,Columns, PrimaryKeysandForeignKeysusingERwin: IntroductiontoERwin How-To:CreateTablesandColumns Usethe“Entity”Tool inorder toCreateNewTables Use<Tab>and<Enter>inordertogivethe TablesaNameandtocreateColumns. Usethe<Arrows>toswitchbetweenthe Columns insideaTable IntroductiontoERwin How-To:CreatePrimaryKey(PK)– ForeignKey(FK)Relationships: Usethe“Relationship”ToolinordertoCreateaPrimary Key (PK) – Foreign Key(FK) Relationship ClickfirstonthePKtableandthenontheFKtableusing the“Relationship” Tool.TheRelationship Connection isthenCreatedAutomatically IntroductiontoERwin Makesuretoset proper DataTypes YoumayalsoDouble-click(orRight-clickand selectTable/ColumnProperties) on Tables andColumns inorder tochangedifferent Attributes,eg.DataTypes,etc. FinalResults: How-To:CreateaSQLScript IntroductiontoERwin 1 Select“ForwardEngineering ” and“Schema...” 2 Makesureyou areusing thePhysical Model 3 4 Select/DeselectdifferentOptions inordertomakeyourscriptthe wayyouwant.Click “Preview”in ordertoseetheresults. Click“Save”whenyouare satisfied withyourScript OpenSQLServerandcreate a“NewDatabase...” 1 3 SQLServer YouareFinished. Start insertingsomtestdata,etc. 2 OpentheSQLScriptinorderto inserttheTablesinSQLServer DatabaseDesignExercise Students: CreatethisExampleusing ERwin. CreatetheTablesinSQLServer. Hans-PetterHalvorsen,M.Sc. UniversityCollegeofSoutheastNorway www.usn.no E-mail:[email protected] Blog:http://home.hit.no/~hansha/