【计算机类职业资格】数据库工程师-22及答案解析.doc

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1、数据库工程师-22 及答案解析(总分：100.00，做题时间：90 分钟)一、选择题(总题数：40，分数：80.00)1.在 PSK 调制方式中，如果一种 modem 的调制速率为 9600baud，采用的是 8 相调制，那么这种 modem 的数据传输速率可达到（分数：2.00）A.14.4KbpsB.28.8KbpsC.64KbpsD.9600bps2.误码率是描述数据通信系统质量的重要参数之一，对误码率人们提出了以下四种看法，请指出哪一种看法是正确的？（分数：2.00）A.误码率是衡量数据通信系统正常工作状态下传输可靠性的参数B.当用户一次传输 1Kbyte 的文件时，没有发现传输错误，

2、那么该数据传输系统的误码率为 0C.当一个数据传输系统采用 CRC 校验技术后，这个数据传输系统的误码率可以减少为 0D.采用光纤作为传输介质的数据传输系统的误码率为 03.数据通信中曼彻斯特编码的波形如下图所示： 请指出它所表示的二进制比特序列的值（分数：2.00）A.1011001101B.1101110110C.1001100010D.11010011104.XMODEM 与 Kermit 协议共同之处是定义了多种类型的信息包来控制通信过程，如采用 ASCII 码字符 SOH表示数据包的开始、EOT 表示文件传输结束等。根据数据链路层协议的分类方法，它们应属于（分数：2.00）A.面向字

3、符型通信协议B.面向比特型通信协议C.随机争用型通信协议D.网络层协议5.在 HDLC 协议执行过程中，数据链路被置为正常响应模式 NRM。如果主站发送的数据帧中，N(S)=2、P=0、N(R)=3；从站正确接收了该帧，并有一个数据帧需要发送。那么，从站能否立即向主站发送这个数据帧，如果可以立即发送的话，那么这个数据帧的控制域参数 N(S)、N(R)、P/F 应该是什么值?（分数：2.00）A.从站不能立即向主站发送数据帧B.从站可以立即向主站发送数据帧，帧控制域参数 N(S)=3，F=0，N(R)=3C.从站可以立即向主站发送数据帧，帧控制域参数 N(S)=3，F=1，N(R)=2D.从站可

4、以立即向主站发送数据桢，桢控制域参数 N(S)=2，F=0，N(R)=36.典型的局域网操作系统的系统容错(SFT)分为三级，最高一级系统容错采用（分数：2.00）A.磁盘镜像B.磁盘双工C.服务器镜像D.网卡冗余7.对于 IEEE 802.3、802.4 与 802.5 三种类型局域网互连的组合中，从 802.3 到 802.3 的网桥设计最简单，只有一种情况会产生问题，那就是（分数：2.00）A.当转发的帧超过最大帧长度时，只能丢弃该帧B.当局域网负载很重，待传送的帧在网桥中堆积，超过了缓冲区空间时，只能将帧丢弃C.如何设置帧优先级D.如何设置数据传输速率8.网络文件访问是网络系统的基本功

5、能，TCP/IP、XNS 与 SNA 均有网络文件访问协议。网络文件访问包括两种不同的形式：文件传输与文件访问。文件访问又叫做在线访问(on-lineaccess)，它（分数：2.00）A.要求用户直接将远地文件全部拷贝到本地文件系统B.允许多个远地程序同时访问单个文件，在原文件上进行操作，而没有文件拷贝过程C.要求本地用户连入局域网中D.要求用户通过电子邮件方式交换信息9.ATM 是一种面向连接的快速分组交换技术，它采用虚拟通道模式，通道标识基于两种标识符（分数：2.00）A.(N)PDU、(N)IDUB.VPI、VCIC.CONNECT .reguest、CONNECT.indicatio

6、nD.(N)SAP、(N+1)SAP10.在 ISO“开放系统互连管理框架“中，将网络系统管理划分为五个功能域。这五个功能域是：配置管理、故障管理、安全管理、性能管理与（分数：2.00）A.设备管理B.用户注册管理C.计费管理D.域名管理11.What is the decimal value of the following 32-bit two“s complement number? 1111 1111 1111 1111 1111 1111 1100（分数：2.00）A.-8B.-4C.4D.812.How many subsets does A have? Let A=E，O，A，W

7、，P，V，B（分数：2.00）A.12B.36C.64D.12813.Suppose V1=，V2=，where R is the set of real numbers，+， and are respectively addition and multiplication. Let f: RR and f(x)=ex， which of the following propositions is true?（分数：2.00）A.f is a surjective homomorphism from V1 to V2B.f is an injective homomorphism from V

8、1 to V2C.f is an isomorphism from V1 to V2D.None of the above14.P(n) is the predicate “if 4 divides n then 2 divides n“. What is the truth value of P(12)?（分数：2.00）A.10BFCTD.None of the above15.An algorithm to solve a given problem has time complexity T(n)=nlog2n-(n-1) Given that the algorithm takes

9、0.8 second for a problem in which n=1024, how long should it take for a problem in which n=4096? (2 Points)（分数：2.00）A.39 secondsB.3.9 secondsC.3.9 minutesD.0.8 seconds16.What is the definition of a Path?（分数：2.00）A.A sequence of vertices and the edges formed by each successive pair of vertices.B.A wa

10、lk with distinct vertices.C.A walk with distinct edges.D.None of the above17.The figure below shows a record used for recording information about a named event. Which of the following statement is incorrect? VAR r : record event : array110 of char; place : array120 of record plname : array115 of cha

11、r; date : array15 of record mo : 112; day : 131; year : integer end end end;（分数：2.00）A.This is a one-dimensional array of records, also called a table.B.This is so called record of arrays;C.The event can occur in up to 20 places and on up to 5 different dates in each place.D.A reference to r.placei.

12、datej.mo will access the month of the jth occurrence, in the ith place, of the event named in r.event.18.Which of the following statements is true regarding simple sort techniques? (2 Points)（分数：2.00）A.Exchange sort is frequently referred to as a bubble sort.B.Exchange sort is the least expensive.C.

13、If random data are in an array that is to be sorted, an Insertion Sort will give the best performance for large elements with small sort items.D.Both Insertion Sort and Selection Sort require O(n)moves.19.Which UNIX command creates a symbolic link named myfile in the current directory to the file/et

14、c/hosts?（分数：2.00）A.In -s /etc/hosts myfileB.In -s myfile/etc/hostsC.link -s/etc/hosts myfileD.link -s myfile/etc/hosts20.Which MS-DOS command is correct?（分数：2.00）A.DEL /s *.batB.DEL *.exe/spC.DEL *,objnul:D.DEL *.corn *.sys21.A virtual memory system has five virtual pages numbered zero through four

15、and three page frames. All the page frames are initially empty. How many page faults are generated with the following access sequence using a FIFO replacement policy? (2 Points) 0 1 2 3 0 1 4 0 1 2 3 4（分数：2.00）A.8B.9C.10D.1122.Which element is NOT part of a microkernel? (2 Points)（分数：2.00）A.basic I/

16、OB.a file systemC.IPC mechanismsD.memory management23.Which is local to a thread instead of a process? (2 Points)（分数：2.00）A.a stackB.an open fileC.a semaphoresD.an address space24.What is a subselect statement?（分数：2.00）A.a select statement that selects a subset of fields in a tableB.a select stateme

17、nt that returns a subset of the data in a tableC.a select statement that appears within another select statementD.a select statement that returns a subset of the constraints on a field25.In developing a hospital database, it is determined that on the average, each patient will have 6 treatments duri

18、ng a hospital stay, The averge length of a stay is three days. The hospital has 1000 beds. There are on the average 800 patients occupying beds each day. The relationship between PATIENT and TREATMENT is I:M. The relationship between PATIENT and BED is 1:1, conditional. If treatment record occurrenc

19、es are archived as soon as a patient is discharded from the hospital, how many occurrences of the TREATMENT records will be stored in the TREATMENT database file on the average? (2 Points（分数：2.00）A.6,000B.4,800C.18,000D.1,60026.Which of the following conditions will make a relation that is in first

20、normal form to be in second normal form? . every non-key attribute is functionally dependent on the full set of primary key attributes. . no non-key attributes exist in the relation. . the primary key consists of only one attribute.（分数：2.00）A.onlyB.and onlyC.and onlyD.any of them27.The most commonly

21、 used locking level in implementing concurrency control is at which of the following levels?（分数：2.00）A.databaseB.tableC.recordD.field28.Which function is NOT served by building a prototype?（分数：2.00）A.It takes the place of the final system.B.It assists in gathering software requirementsC.It assists i

22、n estimating the cost of the project.D.It is used as the foundation of the larger projects.29.Software document is an important part of software and a basis of software development phase. It also influnces software“s (2 Points)（分数：2.00）A.ReusabilityB.MaintanenceC.ExpansibilityD.Portability30.Which p

23、hase of the software development requires the most development time?（分数：2.00）A.the design phaseB.the testing phaseC.the maintenance phaseD.the development phase31.Which of the following statements is correct? (2 Points)（分数：2.00）A.The definition phase results in the Software Requirements Specificatio

24、n.B.Testing is optional in software life cycle.C.CASE tools can only aid in the design phase of a software life cycle.D.A change during a later phase does not require the documentation of all earlier phases to be updated.32.Black-box and white-box testing method are often used in software testing ph

25、ase, in which, the white-box is mainly used to test software“s（分数：2.00）A.reasonableness of structureB.correctness of a programC.external function of a programD.internal logic of a program33.How does Booth“s Algorithm improve binary multiplication?（分数：2.00）A.It prevents overflow.B.It prevents underfl

26、ow.C.It preserves the sign of the multiplication operation.D.It enhances the speed of the operation significantly.34.A cache has 64 blocks; each block is 16 bytes. Which block does byte 1200 map to ?（分数：2.00）A.25B.60C.75D.10035.Which is NOT a characteristic of an RISC processor?（分数：2.00）A.a high clo

27、ck speedB.a highly optimized pipelineC.a few general-purpose registersD.a limited amount of small instructions36.You are performing two sums: the first is a sum of two scalar variables and the second is a matrix sum of a pair of two-dimensional arrays-size 1000 by 1000. What speedup is achieved when

28、 the calculations are performed on size 1000 processors? (2 Points)（分数：2.00）A.50B.100C.999D.none of the above37.According to Shannon“s equation, what is the channel capacity of an analog voice-grade phone line with a bandwidth of 3100 Hz and a signal-to-noise ratio or 30dB? (2 Points)（分数：2.00）A.9.1

29、KbpsB.9.3 KbpsC.30.9 KbpsD.30.17 Kbps38.The X . 25 standard specifies three layers of functionality. Which layers of the OSI model correspond to the X . 25 layers?（分数：2.00）A.the Physical, Network, and Session LayersB.the Physical, Data Link, and Network LayersC.the Physical, Data Link, and Transport

30、 LayersD.the Physical, Session, and Presentation layers39.Which routing algorithm is described below? It is a mechanism in which the setding station determines the route the frame will follow and includes the routing information with the frame; bridges read the routing information to determine if th

31、ey should forward the frame.（分数：2.00）A.Fixed RoutingB.Spanning TreeC.Source RoutingD.Frame Forwarding40.Which OSI layer does a bridge operate at?（分数：2.00）A.the Physical LayerB.the Network LayerC.the Transport LayerD.the Data Link Layer二、论述题(总题数：2，分数：20.00)在计算机指令集的设计与实现过程中，出现了两种对立的技术路线或风格，即 CISC 与 RI

32、SC.（分数：12.00）(1).指出 CISC 的主要弊病（分数：4.00）_(2).概述 RISC 技术的基本要点（分数：4.00）_(3).Intel86 系列属于哪一种风格，当前它采用的是怎样的技术路线（分数：4.00）_人们在管理实践中发现，数据库技术是信息资源的整理、保存、管理和使用的最有效的手段。数据库按其数据结构模型分类，通常可分为层次型数据库、网络型数据库、关系型数据库和面向对象型数据库，各种类似的数据模型都有自身的特点。试从关系数据模型的优点和弱点论述：（分数：8.00）(1).为什么人们在升发以事务处理为主的信息系统(例如管理信息系统)时，大多选用关系型数据库作为开发环境

33、?（分数：4.00）_(2).在许多含有复杂数据结构或丰富语义的实际应用领域中，为什么要选用面向对象数据库或要对关系型数据库作某些扩充和修改?（分数：4.00）_数据库工程师-22 答案解析(总分：100.00，做题时间：90 分钟)一、选择题(总题数：40，分数：80.00)1.在 PSK 调制方式中，如果一种 modem 的调制速率为 9600baud，采用的是 8 相调制，那么这种 modem 的数据传输速率可达到（分数：2.00）A.14.4KbpsB.28.8Kbps C.64KbpsD.9600bps解析：2.误码率是描述数据通信系统质量的重要参数之一，对误码率人们提出了以下四种看

34、法，请指出哪一种看法是正确的？（分数：2.00）A.误码率是衡量数据通信系统正常工作状态下传输可靠性的参数 B.当用户一次传输 1Kbyte 的文件时，没有发现传输错误，那么该数据传输系统的误码率为 0C.当一个数据传输系统采用 CRC 校验技术后，这个数据传输系统的误码率可以减少为 0D.采用光纤作为传输介质的数据传输系统的误码率为 0解析：3.数据通信中曼彻斯特编码的波形如下图所示： 请指出它所表示的二进制比特序列的值（分数：2.00）A.1011001101B.1101110110 C.1001100010D.1101001110解析：4.XMODEM 与 Kermit 协议共同之处是定

35、义了多种类型的信息包来控制通信过程，如采用 ASCII 码字符 SOH表示数据包的开始、EOT 表示文件传输结束等。根据数据链路层协议的分类方法，它们应属于（分数：2.00）A.面向字符型通信协议 B.面向比特型通信协议C.随机争用型通信协议D.网络层协议解析：5.在 HDLC 协议执行过程中，数据链路被置为正常响应模式 NRM。如果主站发送的数据帧中，N(S)=2、P=0、N(R)=3；从站正确接收了该帧，并有一个数据帧需要发送。那么，从站能否立即向主站发送这个数据帧，如果可以立即发送的话，那么这个数据帧的控制域参数 N(S)、N(R)、P/F 应该是什么值?（分数：2.00）A.从站不能立

36、即向主站发送数据帧 B.从站可以立即向主站发送数据帧，帧控制域参数 N(S)=3，F=0，N(R)=3C.从站可以立即向主站发送数据帧，帧控制域参数 N(S)=3，F=1，N(R)=2D.从站可以立即向主站发送数据桢，桢控制域参数 N(S)=2，F=0，N(R)=3解析：6.典型的局域网操作系统的系统容错(SFT)分为三级，最高一级系统容错采用（分数：2.00）A.磁盘镜像B.磁盘双工C.服务器镜像 D.网卡冗余解析：7.对于 IEEE 802.3、802.4 与 802.5 三种类型局域网互连的组合中，从 802.3 到 802.3 的网桥设计最简单，只有一种情况会产生问题，那就是（分数：2

37、.00）A.当转发的帧超过最大帧长度时，只能丢弃该帧B.当局域网负载很重，待传送的帧在网桥中堆积，超过了缓冲区空间时，只能将帧丢弃 C.如何设置帧优先级D.如何设置数据传输速率解析：8.网络文件访问是网络系统的基本功能，TCP/IP、XNS 与 SNA 均有网络文件访问协议。网络文件访问包括两种不同的形式：文件传输与文件访问。文件访问又叫做在线访问(on-lineaccess)，它（分数：2.00）A.要求用户直接将远地文件全部拷贝到本地文件系统B.允许多个远地程序同时访问单个文件，在原文件上进行操作，而没有文件拷贝过程 C.要求本地用户连入局域网中D.要求用户通过电子邮件方式交换信息解析：9

38、.ATM 是一种面向连接的快速分组交换技术，它采用虚拟通道模式，通道标识基于两种标识符（分数：2.00）A.(N)PDU、(N)IDUB.VPI、VCI C.CONNECT .reguest、CONNECT.indicationD.(N)SAP、(N+1)SAP解析：10.在 ISO“开放系统互连管理框架“中，将网络系统管理划分为五个功能域。这五个功能域是：配置管理、故障管理、安全管理、性能管理与（分数：2.00）A.设备管理B.用户注册管理C.计费管理 D.域名管理解析：11.What is the decimal value of the following 32-bit two“s co

39、mplement number? 1111 1111 1111 1111 1111 1111 1100（分数：2.00）A.-8B.-4 C.4D.8解析：12.How many subsets does A have? Let A=E，O，A，W，P，V，B（分数：2.00）A.12B.36C.64D.128 解析：13.Suppose V1=，V2=，where R is the set of real numbers，+， and are respectively addition and multiplication. Let f: RR and f(x)=ex， which of t

40、he following propositions is true?（分数：2.00）A.f is a surjective homomorphism from V1 to V2B.f is an injective homomorphism from V1 to V2 C.f is an isomorphism from V1 to V2D.None of the above解析：14.P(n) is the predicate “if 4 divides n then 2 divides n“. What is the truth value of P(12)?（分数：2.00）A.10B

41、FCT D.None of the above解析：15.An algorithm to solve a given problem has time complexity T(n)=nlog2n-(n-1) Given that the algorithm takes 0.8 second for a problem in which n=1024, how long should it take for a problem in which n=4096? (2 Points)（分数：2.00）A.39 secondsB.3.9 seconds C.3.9 minutesD.0.8 sec

42、onds解析：16.What is the definition of a Path?（分数：2.00）A.A sequence of vertices and the edges formed by each successive pair of vertices.B.A walk with distinct vertices. C.A walk with distinct edges.D.None of the above解析：17.The figure below shows a record used for recording information about a named ev

43、ent. Which of the following statement is incorrect? VAR r : record event : array110 of char; place : array120 of record plname : array115 of char; date : array15 of record mo : 112; day : 131; year : integer end end end;（分数：2.00）A.This is a one-dimensional array of records, also called a table. B.Th

44、is is so called record of arrays;C.The event can occur in up to 20 places and on up to 5 different dates in each place.D.A reference to r.placei.datej.mo will access the month of the jth occurrence, in the ith place, of the event named in r.event.解析：18.Which of the following statements is true regar

45、ding simple sort techniques? (2 Points)（分数：2.00）A.Exchange sort is frequently referred to as a bubble sort. B.Exchange sort is the least expensive.C.If random data are in an array that is to be sorted, an Insertion Sort will give the best performance for large elements with small sort items.D.Both I

46、nsertion Sort and Selection Sort require O(n)moves.解析：19.Which UNIX command creates a symbolic link named myfile in the current directory to the file/etc/hosts?（分数：2.00）A.In -s /etc/hosts myfile B.In -s myfile/etc/hostsC.link -s/etc/hosts myfileD.link -s myfile/etc/hosts解析：20.Which MS-DOS command is

47、 correct?（分数：2.00）A.DEL /s *.batB.DEL *.exe/spC.DEL *,objnul: D.DEL *.corn *.sys解析：21.A virtual memory system has five virtual pages numbered zero through four and three page frames. All the page frames are initially empty. How many page faults are generated with the following access sequence using

48、a FIFO replacement policy? (2 Points) 0 1 2 3 0 1 4 0 1 2 3 4（分数：2.00）A.8B.9 C.10D.11解析：22.Which element is NOT part of a microkernel? (2 Points)（分数：2.00）A.basic I/OB.a file system C.IPC mechanismsD.memory management解析：23.Which is local to a thread instead of a process? (2 Points)（分数：2.00）A.a stack B.an open fileC.a semaphoresD.an address space解析：24.What is a subselect statement?（分数：2