[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$fuAMQGzuKzvea_DzG8nNyMdNOc51kxVOWoeVsLjd2lo4":3},{"answer":4,"createTime":5,"id":6,"options":7,"origin":12,"question":19,"related":20,"source":31,"type":32},[],"2023-09-16 16:47:48",97010496,[8,9,10,11],"AB","BE","CD","DE",{"count":13,"courseId":14,"courseImg":15,"courseName":16,"workId":17,"workName":18},9,"a5cf75222040458920c91d271ef658bd","https:\u002F\u002Ftihai-oss-cloud.itihey.com\u002Fimg\u002Fc725383633da56477eb636ac859d2359.jpg","数据库系统","93615899127d4010a0a9665a2115ee10","06试题","已知关系模式R(A,B,C,D,E),及其上的函数相关性集合F={A→D ,B→C,E→A},该关系模式的候选码是( )",[21,33,42,45,54,63,72,81,90],{"answer":22,"createTime":23,"id":24,"options":25,"question":30,"source":31,"type":32},[],"2023-09-16 16:47:47",97010490,[26,27,28,29],"关系规范化理论","关系代数理论","数理逻辑","关系运算理论","为了设计出性能较优的关系模式,必须进行规范化,规范化主要的理论依据是( )","v1",0,{"answer":34,"createTime":5,"id":35,"options":36,"question":41,"source":31,"type":32},[],97010493,[37,38,39,40],"长度不变的","不可分解的","互相关联的","互不相关的","规范化理论是关系数据库进行逻辑设计的理论依据,根据这个理论,关系数据库中的关系必须满足:每一个属性都是( )",{"answer":43,"createTime":5,"id":6,"options":44,"question":19,"source":31,"type":32},[],[8,9,10,11],{"answer":46,"createTime":5,"id":47,"options":48,"question":53,"source":31,"type":32},[],97010499,[49,50,51,52],"插入、删除、更新异常和数据冗余","提高查询速度","减少数据操作的复杂性","保证数据的安全性和完整性","关系数据库规范化是为了解决关系数据库中的( ) 问题而引入的",{"answer":55,"createTime":5,"id":56,"options":57,"question":62,"source":31,"type":32},[],97010500,[58,59,60,61],"容易产生错误","容易产生冲突","无关紧要","由基本数据导出","数据库中的冗余数据是指( )的数据",{"answer":64,"createTime":5,"id":65,"options":66,"question":71,"source":31,"type":32},[],97010501,[67,68,69,70],"I和II","I和III","I","II","在关系规范化过程中,分解关系的基本原则是( )I. 实现无损失连接 II.分解后的关系相互独立 III.保持原有的函数依赖关系",{"answer":73,"createTime":5,"id":74,"options":75,"question":80,"source":31,"type":32},[],97010502,[76,77,78,79],"是无损失联接,也是保持函数依赖的分解","是无损失联接,但不保持函数依赖的分解","不是无损失联接,但保持函数依赖的分解","既不是无损失联接,也不保持函数依赖的分解","设关系模式R(A,B,C),F是R上成立的函数依赖集合,F={B→C},则分解P={AB,BC}相对于F( )",{"answer":82,"createTime":5,"id":83,"options":84,"question":89,"source":31,"type":32},[],97010504,[85,86,87,88],"C","(H,R)","(H,T)","(H,S)","第8到第9题基于以下的叙述:有关系模式A(C,T,H,R,S),其中各属性的含义是:属性C代表课程名,属性T代表教师姓名,属性H代表上课时间,属性R代表上课教室,属性S代表学生姓名. 根据语义有如下函数依赖集:F={ C→T,(H,R) →C,(H,T)→R, (H,S)→R}.8.请问该关系模式A的候选码是( )",{"answer":91,"createTime":5,"id":92,"options":93,"question":98,"source":31,"type":32},[],97010505,[94,95,96,97],"1NF","2NF","3NF","BCNF","关系模式A的规范化程度最高达到( )"]