数据库选择判断题中英文.docx

1、1. A primary key is a field (or group of fields) that uniquely describes each record in the database. T2. Data redundancy improves the integrity of a database. 3. SQL is the language used by relational databases to create objects and to manipulate and retrieve data.4. A relational database managemen

2、t system does not include tools for backing up & restoring databases. 5. 1，一种主键是一个字段（或字段组）唯一地描述了每个记录在数据库中。6. 2.数据冗余改善了数据库的完整性。7. 3，SQL是关系型数据库用于创建对象，并以操作和检索数据的语言。8. 4.关系数据库管理系统并不包括用于备份和恢复数据库的工具。9. An attribute is also known as a row in most databases. 10. An association between entities is known as a

3、 relationship. 11. Integrity constraints limit the number of entities that can be placed in a table or database. 12. The Entity-Relationship data model is often used in the physical design phase.13. The concept “relation” in relation model is exactly the same as the concept “relationship” in ER mode

4、l.14. 9.一种属性也被称为一个行中大多数数据库。15. 10.实体之间的关联称为关系。16. 11.完整性约束限制可以被放置在一个表或数据库实体的数目。17. 12.实体关系数据模型中经常使用的物理设计阶段。18. 13.在关系模型的概念关系是完全一样的ER模型的概念的“关系”。19. Most relationship sets in a database system involves two entity sets.20. The closure of an attribute set contains that attribute set.21. Lossless decompo

5、sition is necessary in a decomposition algorithm.22. If A B and C D hold, then AC BD also holds.23. It is not necessary that a legal schedule preserves the order in which the instructions appear in each individual transaction.24. Update operations in database must be written into log before updating

6、 database.25. 19.大多数关系套在数据库系统中包括两个实体集。26. 设置属性20.关闭包含的属性设置。27. 21.无损分解是必要的分解算法。28. 22.如果AB和Cd握住，然后ACBD还持有。29. 23.这是没有必要，一个法律时间表保留在其中的指令出现在每个单独的事务处理的次序。30. 在数据库24的更新操作必须写入日志更新数据库之前。未知答案：1. At its simplest, a database can be seen as a collection of related data. 2. If a salesperson attempts to order m

7、erchandise for a customer not in the customer service database, the database will typically generate an error message. This message indicates that an integrity constraint has been violated. 3. An advantage of using a relational database is to facilitate consistency. 4. With the six basic operations

8、(union, difference, selection, projection, product, and renaming), relational algebra is complete. Other operations are just syntactic sugar and can be derived from the basic operations.5. Once a transition is committed, the changes it has made to database persist across system crashes, that is, con

9、sistency.6. 1.在其最简单的，数据库可以被看作是相关的数据的集合。7. 2.如果营业员试图订购商品的顾客不是在客户服务数据库，该数据库将典型地产生一个错误信息。此消息表明完整性约束已经被破坏。8. 3.使用关系数据库的一个优点是便于一致性。9. 4.在六种基本操作（集，差，选择，投影，产品和重命名），关系代数完成。其他的操作都只是语法糖，并且可以从基本操作得到的。10. 5.一旦过渡被提交，已作出的数据库中的改变持续整个系统崩溃，即，一致性。1. _ is the most widely used data model A. relational model B. entity-r

10、elationship modelC. object-based data model D. semi-structured data model 是最广泛使用的数据模型A.关系模型B.实体关系模型C.基于对象的模型数据D.半结构化的数据模型一个关系模式是一组_。A.元组B.属性C.列D.行2. A relation schema is a set of _.A. tuples B. attributes C. columns D. rows3.一组属性，这些属性，采取集体，使我们能够唯一标识关系中的一个元组被称为_的。A.超键B.主键C.候选键D.外键3. A set of attribut

11、es that, taken collectively, allow us to identify uniquely a tuple in the relation is called _.A. super key B. primary key C. candidate key D. foreign key4.应用程序用户在_级数据交互。A.物理B.逻辑C.查看D.以上所有的4. Application users interact with data in the _ level.A. physical B. logical C. view D. all of the above5.关系代数

12、是_语言A.程序B.声明C.自然D.商业5. Relational algebra is a _ languageA. procedural B. declarative C. natural D. commercial6.关系代数的基本操作包括_。A.广义投影，聚合函数，外部联接B.设置交集，自然连接，分立，转让C.选择，项目设置工会，设置不同，笛卡尔积，重命名D.设置路口，设置工会，设置不同的6. The fundamental operations of relational algebra includes_.A. generalized projection, aggregate f

13、unction, outer joinB. set-intersection, natural join, division, assignmentC. select, project, set-union, set-difference, Cartesian product, renameD. set-intersection, set-union, set-difference7.如果表S有M列，表T具有N列，那么S和T的笛卡尔积具有_列。A.M。* N B. M-N C. M + N D. M + N-17. If table S has M columns, table T has N

14、 columns, then the Cartesian product of S and T has _ columns.A. M*N B. M-N C. M+N D. M+N-18.关系代数的_操作需要两个参与关系有属性的数相同。A.师B.参加C.笛卡尔积D.单位8. The _ operation in relational algebra requires the two participating relations have the same number of attributes.A. division B. join C. Cartesian product D. union

15、9. _不包含在SQL语言？A.查询评估B.完整性C.查看D.授权9. _is not contained in SQL language? A. query evaluation B. integrity C. view D. authorization10. 在SQL语句选择关键字对应关系代数的_操作。A.选择B.投影C.参与D.鸿沟10. The SELECT keyword in a SQL statement corresponds to the _ operation in relational algebra.A. select B. projection C. join D.

16、divide 11. SQL语言用_语句从数据库中删除表。A.废除B.删除C.卸下D. DROP11. SQL language use the _ statement to remove a table from database.A. REVOKE B. DELETE C. REMOVE D. DROP 12.使用视图是_有益的。A.并发控制B.安全C.故障恢复D.以上所有的12. Using views is beneficial to _.A. concurrency control B. security C. failure recovery D. all of the above

17、13.触发器可以定义一些要执行的动作_在数据库中的一些事件。A.C。，代替D.后B之前所有上述13. A trigger can define some actions to be executed _ some events in database.A. before B. after C. instead of D. all of the above14. _不是ER模型的基本概念。A.实体B.关系C.程度D.属性S的14. _ is not the basic notions of the E-R model.A. entity B. relationship C. degree D.

18、attribute15.如果映射基数从实体集合S到实体集T是一对多，则T的实体与_实体相关联（实体）答：一个B.最多一个C.至少一个D.多15. If the mapping cardinality from entity set S to entity set T is one to many, then an entity of T is associated with _ entity(entities) of S.A. one B. at most one C. at least one D. many16.一种通过该关系被视为更高级别的抽象实体被称为_。A.聚集B.泛化C.专业化D.

19、属性继承16. An abstraction through which relationships are treated as higher-level entities is called _.A. aggregation B. generalization C. specialization D. attribute inheritance17.映射ER图到关系模式可以在该阶段发生_。A.需求分析B.概念设计C.逻辑设计D.物理设计17. Mapping an E-R diagram into relation schemas can happen in the phase of _.

20、A. requirement analysis B. conceptual design C. logical design D. physical design18. _关系组表示为与两个参与实体集的主键属性的模式。A.一到1 B.一到多C.许多对一D.多对许多18. A _ relationship set is represented as a schema with attributes for the primary keys of the two participating entity sets.A. one-to-one B. one-to-many C. many-to-on

21、e D. many-to-many19.从函数依赖集F = AB，BCD，C，我们可以推断that_。A.交流ABCDE B. BCABCDE C. CDABCDE D.以上都不是19. From the functional dependency set F=AB, BCD, CE, we can infer that_.A. ACABCDE B. BCABCDE C. CDABCDE D. none of the above20. _消除了可以基于函数依赖发现的所有冗余A. 1NF B. 2NF C. 3NF D. BCNF20. _ eliminates all redundancy t

22、hat can be discovered based on functional dependenciesA. 1NF B. 2NF C. 3NF D. BCNF21.我们必须确保_在数据库设计的性能。A. BCNF B.无损分解C.依赖保鲜D. 3NF21. We must ensure the property of _ in database design.A. BCNF B. lossless decomposition C. dependency preservation D. 3NF22. _不是事务的属性A.积极B.一致性C.隔离D.耐久性22. _is not the pro

23、perty of transactions.A. active B. consistency C. isolation D. durability23. _控制并发事务中的交互。答：查询处理器B.存储管理器C.并发控制管理器D.数据库管理员23. _ controls interactions among concurrent transactions.A. query processor B. storage managerC. concurrency control manager D. database administrator24. _of以下指令对不冲突。A.阅读（Q），阅读（Q）

24、B.阅读（Q），写（Q）C.写（Q），阅读（Q）D.写（Q），写（Q）24. _of the following pairs of instructions do not conflict.A. read(Q), read(Q) B. read(Q), write(Q) C. write(Q), read(Q) D. write(Q), write(Q)25.可序列化调度相当于_串行调度（S）。A.只有一个B.至少一个C.至多一个D.任何数量的25. A serializable schedule is equivalent to _ serial schedule(s).A. only on

25、e B. at least one C. at most one D. any number of26.如果一个事务T已经在数据项Q上获得共享锁，则T可以_ Q.A.读取B.写C.读写D.既不会读也不会写交易的S26. If a transaction T has obtain a shared lock on data item Q, then T can _ Q.A. read B. write C. both read and write D. neither read nor write27.时间戳比事务T if_时间戳较小。答：小号提交之前牛逼犯B. S有于T更少的指令C. S使用于

26、T D.S。进入系统牛逼以前少的数据项27. The timestamp of transaction S is smaller than the timestamp of transaction T if_.（什么情况下事务S的时间戳比事务T的时间戳小）A. S commits before T commits B. S has fewer instructions than TC. S uses less data items than T D. S enters the system before T （S比T更早进入系统）28.在时间戳协议，如果TS（TI）TS（TJ），串行化顺序is

27、_。A.交易钛出现交易TJ前B.交易TJ出现交易钛前C.由实际执行确定D.不能确定28. In the timestamp protocol, if TS(Ti)TS(Tj), the serializability order is_.A. transaction Ti appears before transaction TjB. transaction Tj appears before transaction TiC. determined by the actual executionD. not sure29.假设交易T22，T23，T24有时间戳5,10,15，分别。如果T22请

28、求由T23持有的数据项，那么T22将等待。如果请求T24 T23所举办的数据项，那么T24将回滚。这种技术被称为_。A.并行B.饥饿C.等待模D.伤口等待29. Suppose transactions T22, T23, T24 have timestamps 5,10,15, respectively. If T22 requests a data item held by T23, then T22 will wait. If T24 requests a data items held by T23, then T24 will be rolled back. This techniq

29、ue is called _.A. concurrent B. starvation C. wait-die D. wound-wait30. _是不是发生时检查站执行的操作。A.输出到磁盘的所有修改的缓冲块B.输出到目前居住在主内存中的所有日志记录的稳定存储C.执行所有的更新操作D.输出到稳定的存储日志记录30. _ is not the action to take place when checkpoints are performed.A. output onto the disk all modified buffer blocksB. output onto the stable storage all log records currently residing in main memoryC. perform all update actions D. output onto stable storage a log record 1. A collection of interrelated data and a set of programs to access the data is called A. DatabaseB. Database systemC. File system D. DBMS2. A major pur