04735《数据库系统原理》复习题答案
数据库系统原理（课程代码0４７３５）
一、单项选择题（本大题共24小题）在每小题列出的四个备选项中只有一个是最符合题目要求的，请将其代码填写在题后的括号内。错选、多选或未选均无分。
1．DBS具有较高的数据独立性，是因为DBS采用了【 B 】A．嵌入式语言B．三级模式结构
C．DD D．六个层次的存储介质
2．在层次、网状模型中，起导航数据作用的是【A 】A．指针B．关键码
C．DD D．索引
3．设关系R(A,B,C)和关系S(B,C,D), 那么与R?S等价的关系代数表达式是【B 】A．σ2=4（R?S）B．σ2=4（R×S）
C．σ2=1（R?S）D．σ2=1（R×S）
4．设关系R和S的结构相同，分别有m和n个元组，那么R－S操作的结果中元组个数为【 C 】A．为m－n B．为m
C．小于等于m D．小于等于（m－n）
5. 设有两个事务T1、T2，A、B的初始值分别为10和5，其并发操作如图1所示，下面评价正确的是【C 】A．该调度（schedule）不存在并发问题B．该调度是可串行化的(rializable)。
C．该调度存在冲突(conflict)操作D．该调度不存在冲突操作
T1 T2
read(A)
read(B)
sum=A+B
read(A)
A＝A*2
write(A)
read(A)
read(B)
sum=A+B
write(A+B)
图1 事务并发操作图
6．设有关系R（A，B，C）的值如下：
bvi ousl y, face Chi na's S ociali st system, the Communist Party is not the party. In that ca, political cha os has bee n very tight. Is remodeling or reconstructi on, i s a correcti on or a st ove. Whether to tur n right or left, is back t o the sour ce or put forward new poli
tical idea s. This is to determ ine the r oad problems i n China, i s also the key out of the deep water of the reform of t he economic sy stem. After 18, the new Ce ntral collective leader shi p attache s great importance to political orie ntation. First, the "Central eig ht articles" a s a starting poi nt, starting from t he Ce ntral Governme nt's lf-restraint, w hich pre aches a nd pro-image, brought fresh feeling to the community. Secondl y, before reform a nd openi ng up and reform and openi ng two peri ods after non-negative, untying the tangle of the soci ety a long time on this i ssue. T hird, a new ge neration of party leaders on vari ous oc casi ons to Ma o Ze-Dong and Ma o Ze-Dong's
thoug ht of evaluati on has room for manoeuvre, t hrough to t he ruli ng ideol ogy of Ma o Zedong thoug ht, is the call of the soul t o the S ociali st Revoluti on a nd construction. Empty talks je opar dize national interest s and try again, i s an affirmation of Deng Xia o-ping's reform i deas. The strong political signa l showi ng a ne w generati on of politi cal leaders is st ill keepi ng to the Socialist roa d. Four is revisiti ng the "talking t o Mao Z e-Dong's hist orical cycle of" high pr ofile anti-corruption and the im portance of the Constit ution, reorga nization is bad style of officialdom, was t o civil ize people obey t he law, whi
le improvi ng the col or change of the regime of vigilance. Five is to reform into dee per waters a nd stre s d that top-leve l desig n, thi s is a revi ew on the reform a nd ope ning up i n the past, i s also looking for a way out. Six foreign and Russia cl or, the flexible attitude on the issue of t he Korean peni nsula, Si no-Japane fishing
hardli ne China on the island out of the "patie nt" and low profile sha dow began to gradually pl an development. Signs show that the new lea dership began to make a left turn i n politics. However, as of right now, not only i deological confusi on i n the communit y, the new lea dership's t hinki ng is messy. New lea ders both stresd t he nee d to impleme nt the Constitution, stresd the nee d to tur n off the power in a cage. Also stres s that Ma o Zedong thought cannot be l ost, 30 year s after the reform and ope ning up 30 years ag o ca n not deny ea ch other. Both adv ocate democra cy and rele a "ven does not speak of" files of political constraints. Neither deny t he hist ory of the CPC Central Committee on veral i ssues ...
A B C
5 6 5
6 7 5
6 8 6
下列叙述正确的是【 B 】A．函数依赖C→A在上述关系中成立B．函数依赖AB→C在上述关系中成立C．函数依赖A→C在上述关系中成立D．函数依赖C→AB在上述关系中成立7．设关系模式R（A，B，C，D），F是R上成立的FD集，F={ A→C，BC→D }，那么ρ={ ABD，AC }相对于F 【 B 】
A．是无损联接分解，也是保持FD的分解
B．是无损联接分解，但不保持FD的分解
C．不是无损联接分解，但保持FD的分解
D．既不是无损联接分解，也不保持FD的分解
8．概念设计的结果得到的是概念模式。概念模式是【 D 】A．与DBMS有关的B．与硬件有关的
C．独立于DBMS的D．独立于DBMS和硬件的
9．在有关“弱实体”的叙述中，不正确的是【 C 】A．弱实体的存在以父实体的存在为前提
B．弱实体依赖于父实体的存在
C．父实体与弱实体的联系可以是1:1、1:N或M:N
D．父实体与弱实体的联系只能是1:1或1:N
10．有15个实体类型，并且它们之间存在着15个不同的二元联系，其中5个是1:1联系类型，5个是1:N联系类型，5个M:N联系类型，那么根据转换规则，这个ER 结构转换成的关系模式有【 B 】
A．15个B．20个C．25个D．30个
11．关系运算中花费时间可能最长的运算是【C 】A．投影B．选择C．笛卡尔积D．除
12．关系规范化中的插入操作异常是指【D 】A．不该删除的数据被删除B．不该插入的数据被插入
C．应该删除的数据未被删除D．应该插入的数据未被插入
13．数据库在磁盘上的基本组织形式是【B 】A．DB B.文件 C.二维表 D.系统目录
14．在DBS中，最接近于物理存储设备一级的结构，称为【 D 】A．外模式B．概念模式C．用户模式D．内模式
15．从模块结构考察，DBMS由两大部分组成：【 B 】A．查询处理器和文件管理器B．查询处理器和存储管理器
C．数据库编译器和存储管理器D．数据库编译器和缓冲区管理器
State key protection of capital i nterests rather than the i nterests of citi zens, ha d bee n hits t he bottom of the pr oletariat
16．设W=R?S，且W、R、S的属性个数分别为w、r和s，那么三者之间应满
