数据库系统习题1参考答案[12分]用英文解释：Transaction：Atransactionisaunitofprogramexecutionthataccessesandpossiblyupdatesvariousdataitems.DBMS：Adatabasemanagementsystemconsistsofacollectionofinterrelateddataandacollectionofprogramstoaccessthatdata.Datamodel：Acollectionofconceptualtoolsfordescribingdata,datarelationships,datasemantics,anddataconstraints.[20分]填空题（在下列各小题中的括号部分省略了数据库系统的术语，在答题纸上写好小题号，并在其后用英文填写相应的术语）：An(entity)isanobjectthatexistsintherealworldandisdistinguishablefromotherobjects.Theoveralldesignofthedatabaseiscalledthe(databaseschema).WesaythatascheduleSis(conflictserializable),ifitisconflictequivalenttoaserialschedule.A(relation)isanassociationamongseveralentities.LetRbearelationschema.AsubsetKofRisa(superkey)ofRif,inanylegalrelationr(R),forallpairst1andt2oftuplesinrsuchthatt1≠t2,thent1[K]≠t2[K].Underlyingthestructureofadatabaseisthe(Datamodel):acollectionofconceptualtoolsfordescribingdata,datarelationships,datasemantics,anddataconstraints.A(DML)isalanguagethatenablesuserstoaccessormanipulatedata.Adatabaseschemaisspecifiedbyasetofdefinitionsthatareexpressedusinga(datadictionary).A(transaction)isaunitofprogramexecutionthataccessesandpossiblyupdatesvariousdataitems.The(lock-basedprotocol)allowsatransactiontolockanewdataitemonlyifthattransactionhasnotyetunlockedanydataitem.三、[8分]请设计一个体育比赛技术统计数据库。数据库对每个运动员保存个人记录，包括：姓名、性别、年龄、身份证号。对每项比赛存有：比赛编号、比赛时间、地点、比分、参加比赛的球队名称。还应记录上场队员在每场比赛的统计数据，包括：进球数、助攻次数。画出相应的E-R图，并加以必要的说明。四、[8分]根据下面的E-R图设计关系数据库，要求指出相应的主键和外键。account(account_number,balance,branch_name)primarykey(account_number)foreignkey(branch_name)branch(branch_name,branch_city,assets)primarykey(branch_name)customer(customer_name,customer_city)primarykey(customer_name)depositor(account_number,customer_name)primarykey(account_number,customer_name)foreignkey(account_number)foreignkey(customer_name)五、[12分]考虑下图所示员工数据库。为下面每个查询语句写出SQL表达式。employee(employee-name,street,city)works(employee-name,company-name,salary)company(company-name,city)ａ.找出不为FirstBankCorp