资源描述：
《E-R建模及关系表转换-例题习题-2014-submitted.doc》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。
1、一、ConsiderthefollowinginformationinanairportdatabaselAnairportisdescribedbyitsnameandthecitythattheairportlocatesatlEachairplanehasanuniqueregistrationnumberandalsothedateofproductionasitsdescriptiveattributeslEachairplanemodelisidentifiedbyamodelnumberandhasacapacit
2、yandaweightlAtechnicianischaracterizedbyanuniquetechnician_id,hisnameandhisphonenumberlEachairportaccommodatesanumberofairplanemodels,andanairplanemodelmayappearsinseveralairports;butsomeairportsarenotsuitableforaccommodaingseveralspecialplanemodels.lEachairplaneisof
3、aspecificmodel,e.g.Boeing737;andforeachmodel,therearemorethanoneairplanebeingofit.lforeachairport,therearesometechniciansworkingthere,andeachtechnicianmustworksatonlyoneairport.lEachtechnicianisresponsibleforoneormoreplanemodels,andeachplanemodelhasatleastonetechnici
4、anresponsibleforitlEachairplaneisperiodicallytestedbyanumberoftechnicianstoensurethattheairplaneisstillairworthy.Atechnicianmaytestseveralairplaneseachyear,andsometimesatechnicianhasnotaskfortestingtheairplanes.Itisrequiredthatwhenatechniciantestsanairplane,theairpla
5、nemodelthatheisresponsibleforisjustthemodelthattheairplanetestedisof.Theinformation,suchasthetestnumber,thetestingdate,thetestingresultandthetimespentonthetest,isneededtodescribeatestingoftheairplane(1)DesigntheE/Rdiagramfortheairportdatabaseonthebasisoftheinformatio
6、nmentionedaboveNote:theprimarykeyoftheentities,mappingcardinalityofeachrelationshipandparticipationofeachentitytotherelationshipshouldbedescribedinthediagram..(10points)(2)ConverttheE-Rdiagramtotheproperrelationalschema,andgivetheprimarykeyofeachrelationschemabyunder
7、lines.(10points)Answers：(2)(10points)实体airport归结为:airport(a-name,city);实体model归结为:model(m-num,weight,capacity);联系accommodate归结为:accommodate(a-name,m-num);实体airplane和联系be-of归结为：airplane(re-num,date,m-num);实体technician、联系work归结为：technician(t-id,t-name,phone-num,a-name)
8、联系test归结为:test(t-id,re-num,t-num,t-date,time,result)联系responsible归结为:responsible(t-id,m-num)一、Auniversitystudentdatabaseneedstostor
