原创力文档- 1、本文档共55页，可阅读全部内容。
- 2、原创力文档（book118）网站文档一经付费（服务费），不意味着购买了该文档的版权，仅供个人/单位学习、研究之用，不得用于商业用途，未经授权，严禁复制、发行、汇编、翻译或者网络传播等，侵权必究。
- 3、本站所有内容均由合作方或网友上传，本站不对文档的完整性、权威性及其观点立场正确性做任何保证或承诺！文档内容仅供研究参考，付费前请自行鉴别。如您付费，意味着您自己接受本站规则且自行承担风险，本站不退款、不进行额外附加服务；查看《如何避免下载的几个坑》。如果您已付费下载过本站文档，您可以点击 这里二次下载。
- 4、如文档侵犯商业秘密、侵犯著作权、侵犯人身权等，请点击“版权申诉”（推荐），也可以打举报电话：400-050-0827(电话支持时间：9:00-18:30)。
COMP231COMP2311RelationalModel
OutlineIntroductionTerminologyER-to-RelationalMappingCOMP2312
IntroductionCOMP2313 TherelationalmodelwasfirstintroducedbyTedCoddofIBMResearchin1970 andattractedduetoitssimplicity,eleganceandmathematicalfoundations Themodelusestheconceptofamathematicalrelation–whichlookslikeatableofvalues
OutlineIntroductionTerminologyER-to-RelationalMappingCOMP2314
TerminologyCOMP2315 Relation?table;denotedbyR(A1,A2,...,An)whereRisarelationnameand(A1,A2,...,An)istherelationschemaofRAttribute(column)denotedbyAiTuple(Record)rowAttributevaluevaluestoredinatablecellDomain???????????????????????????????????????denotedbydom(Ai)Attribute:AgeAttribute:EmpNameAttribute:SalaryDomain:[0-100]Domain:50alphabeticcharsDomain:non-negativeinteger
TerminologyAttributes/Columns(collectivelyasaschema)Tuples/RowsRelationName/TableNameCOMP2316
SchemaTherelationschemais(Name,Student-id,Age,CGA)ORTheprimarykeyisunderlinedintheaboveNameStudent-id AgeCGACOMP2317
ForeignKeyCOMP2318 Aforeignkeyisasetofattributesinonerelationrthatisusedtorefertoatupleinanotherrelations.(itmustcorrespondtotheprimarykeyofthesecondrelation)
ForeignKeyCOMP2319Student(Student-id,Student-Name)Take(Student-id,Course-id,semesterNo) Student-idinrelationStudentisaprimarykeyStudent-idinrelationTakeisaforeignkey
ForeignKeyCOMP23110Student(Student-id,Student-Name)Take(Student-id,Course-id,semesterNo)Course(Course-id,Course-Name)Course-idinrelationCourseisaprimarykeyCourse-idinrelationTakeisaforeignkey
OutlineIntroductionTerminologyER-to-RelationalMappingCOMP23111
ER-to-RelationalMappingCOMP23112 Typically,databasedesignersbeginwiththeERmodel,whichisveryexpressiveanduser-friendlytohuman Then,theERmodelismappedtotherelationalmodelforDBMSmanipulations Databasequeriesandupdateswillbewr
文档评论（0）