《数据库原理及应用》课程作业1
1[单选题].在数据库设计中，将ER图转换成关系数据模型的过程属于
奥鹏作业答案
A.需求分析阶段
B.逻辑设计阶段
C.概念设计阶段
D.物理设计阶段
正确答案:——B——
2[单选题].<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"DBMS中实现事务持久性的子系统是 </SPAN
A.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"安全性管理子系统</SPAN
B.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"完整性管理子系统</SPAN
C.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"并发控制子系统</SPAN
D.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"恢复管理子系统</SPAN
正确答案:——D——
3[单选题].<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"下列聚合函数中不忽略空值 （<SPAN null） 的是</SPAN</SPAN
A.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"SUM （列名）</SPAN
B.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"<SPAN style="mso-spacerun: yes" </SPANMAX （列名</SPAN
C.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"<SPAN style="mso-spacerun: yes" </SPANCOUNT （ * ） </SPAN
D.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"AVG （列名）</SPAN
正确答案:——C——
4[单选题].下列运算中（ ）不是关系代数的基本操作
A.笛卡儿积
B.自然连接
C.投影
D.并
正确答案:————
5[单选题].设有关系R和S，与R-S等价的元组关系演算表达式是
A.{t|R（t）∨┐s（t）}
B.{t|R（t）∧┐S（t）}
C.{t|（u）R（t∨┐S（u））
D.{t| （u）R（t）∧┐S（u）}
正确答案:————
6[单选题].<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-ascii-font-family: 'Arial'; mso-hansi-font-family: 'Arial'"在</SPAN<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt"SQL</SPAN<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-ascii-font-family: 'Arial'; mso-hansi-font-family: 'Arial'"的</SPAN<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt"SELECT</SPAN<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-ascii-font-family: 'Arial'; mso-hansi-font-family: 'Arial'"语句中，实现投影操作的是哪个句？</SPAN
A.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt"SELECT</SPAN
B.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt"FROM</SPAN
C.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt"WHERE</SPAN
D.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt"ORDER BY</SPAN
正确答案:————
7[单选题].数据库系统是在（ ）的基础上发展起来的。
A.文件系统
B.应用程序系统
C.数据库管理系统
D.编译系统
正确答案:————
8[单选题].SQL语言中，创建一个表的命令是
A.View
B.DROP
C.CLEAR
D.Create
正确答案:————
9[单选题].<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"SQL中，下列涉及空值的操作，不正确的是 </SPAN
A.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"<SPAN style="mso-spacerun: yes" </SPANAGE IS NULL</SPAN
B.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"AGE IS NOT NULL</SPAN
C.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"<SPAN style="mso-spacerun: yes" </SPANAGE = NULL</SPAN
D.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"NOT （AGE IS NULL）</SPAN
正确答案:————
10[单选题].下列关于数据库系统特点的叙述中，正确的一项是
A.各类用户程序均可随意地使用数据库中的各种数据
B.数据库系统中概念模式改变，则需将与其有关的子模式做相应改变，否则用户程序需改写
C.数据库系统的存储模式如有改变，概念模式无需改动
D.数据一致性是指数据库中数据类型的一致
正确答案:————
11[单选题].<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"属性类型允许是基本数据类型、结构类型和集合类型的模型是</SPAN
A.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"平面关系模型</SPAN
B.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"嵌套关系模型</SPAN
C.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"复合对象模型</SPAN
D.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"分布式关系模型</SPAN
正确答案:————
12[单选题].关系模型的程序员不需熟悉数据库的
A.数据操作
B.完整性约束条件
C.存取路径
D.数据定义
正确答案:————
13[单选题].有一个网络数据库应用系统，其中一台计算机A存有DBMS软件、所有用户数据和应用程序，其余各节点作为终端通过通信线路向A发出数据库应用请求，这种方式属于
A.集中式数据库体系结构
B.主从式数据库体系结构
C.客户机/服务器数据库体系结构
D.分布式数据库体系结构
正确答案:————
14[单选题].<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: ' '; mso-hansi-font-family: ' '"关系数据库中的视图属于</SPAN<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: ' '; mso-bidi-font-family: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"<FONT face="宋体, MS Song"4</FONT</SPAN<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: ' '; mso-hansi-font-family: ' '"个数据抽象级别中的</SPAN
A.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: '' ''; mso-hansi-font-family: '' ''"外部模型</SPAN
B.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: '' ''; mso-hansi-font-family: '' ''"概念模型</SPAN
C.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: '' ''; mso-hansi-font-family: '' ''"逻辑模型</SPAN<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: '' ''; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"<FONT face="宋体, MS Song" </FONT</SPAN
D.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: '' ''; mso-hansi-font-family: '' ''"物理模型</SPAN
正确答案:————
15[单选题].<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: ' '; mso-bidi-font-family: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"<FONT face="宋体, MS Song"SQL</FONT</SPAN<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: ' '; mso-hansi-font-family: ' '"语言中，删除一个表的命令是</SPAN
A.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: '' ''; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"<FONT face="宋体, MS Song"DELETE </FONT</SPAN
B.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: '' ''; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"<FONT face="宋体, MS Song"DROP</FONT</SPAN
C.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: '' ''; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"<FONT face="宋体, MS Song"CLEAR</FONT</SPAN
D.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: '' ''; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"<FONT face="宋体, MS Song"<SPAN style="mso-spacerun: yes" </SPANREMORE </FONT</SPAN
正确答案:————
16[单选题].<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"在<SPAN DBS中，DBMS和OS之间的关系是</SPAN</SPAN
A.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"相互调用</SPAN
B.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"DBMS调用OS</SPAN
C.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"<SPAN style="mso-spacerun: yes" </SPANOS调用DBMS</SPAN
D.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"并发运行</SPAN</SPAN
正确答案:————
17[单选题].<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: ' '; mso-hansi-font-family: ' '"为了防止一个用户的工作不适当地影响另一个用户，应该采取</SPAN
A.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: '' ''; mso-hansi-font-family: '' ''"完整性控制</SPAN
B.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: '' ''; mso-hansi-font-family: '' ''"安全性控制</SPAN
C.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: '' ''; mso-hansi-font-family: '' ''"并发控制</SPAN
D.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: '' ''; mso-hansi-font-family: '' ''"访问控制</SPAN
正确答案:————
18[单选题].DBMS提供DML实现对数据的操作。可以独立交互使用的DML称为
A.宿主型
B.独立型
C.自含型
D.嵌入型
正确答案:————
19[单选题].位于用户和操作系统之间的一层数据管理软件是
A.DBS
B.DB
C.DBMS
D.MIS
正确答案:————
20[单选题].数据库系统依靠__支持了数据独立性
A.具有封装机制
B.模式分级、各级之间有映像机制
C.定义完整性约束条件
D.DDL语言和DML语言互相独立
正确答案:————
21[单选题].<IMG alt="" hspace=3 src="https://d.az9.cn/d/file/aopengzaixian/2019/1219/11093153820_5.jpg" vspace=1 border=0
A.I，II，IV
B.I，III
C.I，II
D.I，IV ，q76 1296 021
正确答案:————
22[单选题].下列哪一个不是数据库开发的可选数据库。
A.mysql
B. DB2
C.Oracle
D.Excel
正确答案:————
23[单选题].<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"分布式数据库系统中分片模式和分配模式均是</SPAN
A.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"全局的</SPAN
B.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"<SPAN style="mso-spacerun: yes" </SPAN局部的</SPAN
C.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"<SPAN style="mso-spacerun: yes" </SPAN分布的</SPAN
D.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"集中的</SPAN
正确答案:————
24[单选题].<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: ' '; mso-bidi-font-family: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"<FONT face="宋体, MS Song"SQL</FONT</SPAN<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: ' '; mso-hansi-font-family: ' '"语言中，删除记录的命令是</SPAN
A.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: '' ''; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"<FONT face="宋体, MS Song"DELETE</FONT</SPAN
B.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: '' ''; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"<FONT face="宋体, MS Song"DROP</FONT</SPAN
C.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: '' ''; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"<FONT face="宋体, MS Song"<SPAN style="mso-spacerun: yes" </SPANCLEAR</FONT</SPAN
D.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: '' ''; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"<FONT face="宋体, MS Song"REMORE</FONT</SPAN
正确答案:————
25[单选题].<span style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"如果事务<span lang="EN-US"T获得了数据项Q上的排它锁，则T对Q （ ）</span</span
A.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"只能读不能写</SPAN
B.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"只能写不能读<SPAN <BR style="mso-special-character: line-break"<BR style="mso-special-character: line-break"</SPAN</SPAN
C.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"既可读又可写</SPAN
D.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"不能读不能写</SPAN
正确答案:————
附件是答案， 微信7612 96021
1[单选题].在数据库设计中，将ER图转换成关系数据模型的过程属于
奥鹏作业答案
A.需求分析阶段
B.逻辑设计阶段
C.概念设计阶段
D.物理设计阶段
正确答案:——B——
2[单选题].<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"DBMS中实现事务持久性的子系统是 </SPAN
A.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"安全性管理子系统</SPAN
B.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"完整性管理子系统</SPAN
C.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"并发控制子系统</SPAN
D.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"恢复管理子系统</SPAN
正确答案:——D——
3[单选题].<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"下列聚合函数中不忽略空值 （<SPAN null） 的是</SPAN</SPAN
A.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"SUM （列名）</SPAN
B.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"<SPAN style="mso-spacerun: yes" </SPANMAX （列名</SPAN
C.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"<SPAN style="mso-spacerun: yes" </SPANCOUNT （ * ） </SPAN
D.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"AVG （列名）</SPAN
正确答案:——C——
4[单选题].下列运算中（ ）不是关系代数的基本操作
A.笛卡儿积
B.自然连接
C.投影
D.并
正确答案:————
5[单选题].设有关系R和S，与R-S等价的元组关系演算表达式是
A.{t|R（t）∨┐s（t）}
B.{t|R（t）∧┐S（t）}
C.{t|（u）R（t∨┐S（u））
D.{t| （u）R（t）∧┐S（u）}
正确答案:————
6[单选题].<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-ascii-font-family: 'Arial'; mso-hansi-font-family: 'Arial'"在</SPAN<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt"SQL</SPAN<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-ascii-font-family: 'Arial'; mso-hansi-font-family: 'Arial'"的</SPAN<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt"SELECT</SPAN<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-ascii-font-family: 'Arial'; mso-hansi-font-family: 'Arial'"语句中，实现投影操作的是哪个句？</SPAN
A.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt"SELECT</SPAN
B.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt"FROM</SPAN
C.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt"WHERE</SPAN
D.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt"ORDER BY</SPAN
正确答案:————
7[单选题].数据库系统是在（ ）的基础上发展起来的。
A.文件系统
B.应用程序系统
C.数据库管理系统
D.编译系统
正确答案:————
8[单选题].SQL语言中，创建一个表的命令是
A.View
B.DROP
C.CLEAR
D.Create
正确答案:————
9[单选题].<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"SQL中，下列涉及空值的操作，不正确的是 </SPAN
A.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"<SPAN style="mso-spacerun: yes" </SPANAGE IS NULL</SPAN
B.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"AGE IS NOT NULL</SPAN
C.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"<SPAN style="mso-spacerun: yes" </SPANAGE = NULL</SPAN
D.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"NOT （AGE IS NULL）</SPAN
正确答案:————
10[单选题].下列关于数据库系统特点的叙述中，正确的一项是
A.各类用户程序均可随意地使用数据库中的各种数据
B.数据库系统中概念模式改变，则需将与其有关的子模式做相应改变，否则用户程序需改写
C.数据库系统的存储模式如有改变，概念模式无需改动
D.数据一致性是指数据库中数据类型的一致
正确答案:————
11[单选题].<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"属性类型允许是基本数据类型、结构类型和集合类型的模型是</SPAN
A.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"平面关系模型</SPAN
B.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"嵌套关系模型</SPAN
C.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"复合对象模型</SPAN
D.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"分布式关系模型</SPAN
正确答案:————
12[单选题].关系模型的程序员不需熟悉数据库的
A.数据操作
B.完整性约束条件
C.存取路径
D.数据定义
正确答案:————
13[单选题].有一个网络数据库应用系统，其中一台计算机A存有DBMS软件、所有用户数据和应用程序，其余各节点作为终端通过通信线路向A发出数据库应用请求，这种方式属于
A.集中式数据库体系结构
B.主从式数据库体系结构
C.客户机/服务器数据库体系结构
D.分布式数据库体系结构
正确答案:————
14[单选题].<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: ' '; mso-hansi-font-family: ' '"关系数据库中的视图属于</SPAN<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: ' '; mso-bidi-font-family: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"<FONT face="宋体, MS Song"4</FONT</SPAN<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: ' '; mso-hansi-font-family: ' '"个数据抽象级别中的</SPAN
A.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: '' ''; mso-hansi-font-family: '' ''"外部模型</SPAN
B.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: '' ''; mso-hansi-font-family: '' ''"概念模型</SPAN
C.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: '' ''; mso-hansi-font-family: '' ''"逻辑模型</SPAN<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: '' ''; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"<FONT face="宋体, MS Song" </FONT</SPAN
D.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: '' ''; mso-hansi-font-family: '' ''"物理模型</SPAN
正确答案:————
15[单选题].<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: ' '; mso-bidi-font-family: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"<FONT face="宋体, MS Song"SQL</FONT</SPAN<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: ' '; mso-hansi-font-family: ' '"语言中，删除一个表的命令是</SPAN
A.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: '' ''; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"<FONT face="宋体, MS Song"DELETE </FONT</SPAN
B.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: '' ''; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"<FONT face="宋体, MS Song"DROP</FONT</SPAN
C.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: '' ''; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"<FONT face="宋体, MS Song"CLEAR</FONT</SPAN
D.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: '' ''; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"<FONT face="宋体, MS Song"<SPAN style="mso-spacerun: yes" </SPANREMORE </FONT</SPAN
正确答案:————
16[单选题].<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"在<SPAN DBS中，DBMS和OS之间的关系是</SPAN</SPAN
A.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"相互调用</SPAN
B.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"DBMS调用OS</SPAN
C.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"<SPAN style="mso-spacerun: yes" </SPANOS调用DBMS</SPAN
D.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"并发运行</SPAN</SPAN
正确答案:————
17[单选题].<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: ' '; mso-hansi-font-family: ' '"为了防止一个用户的工作不适当地影响另一个用户，应该采取</SPAN
A.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: '' ''; mso-hansi-font-family: '' ''"完整性控制</SPAN
B.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: '' ''; mso-hansi-font-family: '' ''"安全性控制</SPAN
C.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: '' ''; mso-hansi-font-family: '' ''"并发控制</SPAN
D.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: '' ''; mso-hansi-font-family: '' ''"访问控制</SPAN
正确答案:————
18[单选题].DBMS提供DML实现对数据的操作。可以独立交互使用的DML称为
A.宿主型
B.独立型
C.自含型
D.嵌入型
正确答案:————
19[单选题].位于用户和操作系统之间的一层数据管理软件是
A.DBS
B.DB
C.DBMS
D.MIS
正确答案:————
20[单选题].数据库系统依靠__支持了数据独立性
A.具有封装机制
B.模式分级、各级之间有映像机制
C.定义完整性约束条件
D.DDL语言和DML语言互相独立
正确答案:————
21[单选题].<IMG alt="" hspace=3 src="https://d.az9.cn/d/file/aopengzaixian/2019/1219/11093153820_5.jpg" vspace=1 border=0
A.I，II，IV
B.I，III
C.I，II
D.I，IV ，q76 1296 021
正确答案:————
22[单选题].下列哪一个不是数据库开发的可选数据库。
A.mysql
B. DB2
C.Oracle
D.Excel
正确答案:————
23[单选题].<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"分布式数据库系统中分片模式和分配模式均是</SPAN
A.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"全局的</SPAN
B.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"<SPAN style="mso-spacerun: yes" </SPAN局部的</SPAN
C.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"<SPAN style="mso-spacerun: yes" </SPAN分布的</SPAN
D.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"集中的</SPAN
正确答案:————
24[单选题].<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: ' '; mso-bidi-font-family: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"<FONT face="宋体, MS Song"SQL</FONT</SPAN<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 'Arial'; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-ascii-font-family: ' '; mso-hansi-font-family: ' '"语言中，删除记录的命令是</SPAN
A.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: '' ''; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"<FONT face="宋体, MS Song"DELETE</FONT</SPAN
B.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: '' ''; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"<FONT face="宋体, MS Song"DROP</FONT</SPAN
C.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: '' ''; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"<FONT face="宋体, MS Song"<SPAN style="mso-spacerun: yes" </SPANCLEAR</FONT</SPAN
D.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: '' ''; mso-bidi-font-family: ''Arial''; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"<FONT face="宋体, MS Song"REMORE</FONT</SPAN
正确答案:————
25[单选题].<span style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"如果事务<span lang="EN-US"T获得了数据项Q上的排它锁，则T对Q （ ）</span</span
A.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"只能读不能写</SPAN
B.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"只能写不能读<SPAN <BR style="mso-special-character: line-break"<BR style="mso-special-character: line-break"</SPAN</SPAN
C.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"既可读又可写</SPAN
D.<SPAN style="FONT-SIZE: 16px; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"不能读不能写</SPAN
正确答案:————
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