数据库选择判断题.docx

数据库选择判断题1. A primary key is a field (or group of fields) that uniquely describes each record in the database. T 2. 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 management system does not include tools for backing up & restoring databases. 5. 1，一种主键是一个字段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 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 model. 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 decomposition 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 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 merchandise 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 (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, consistency. 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，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-relationship model C. 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. rows 3.一组属性，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 attributes 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 key 4.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 above 5.关系代数是_语言 A.程序B.声明C.自然D.商业 5. Relational algebra is a _ language A. procedural B. declarative C. natural D. commercial 6.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 function, outer join B. set-intersection, natural join, division, assignment C. select, project, set-union, set-difference, Cartesian product, rename D. set-intersection, set-union, set-difference 7.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-1 7. If table S has M columns, table T has N columns, then the Cartesian product of S and T has _ columns. A. M*N B. M-N C. M+N D. M+N-1 8.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 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. authorization 10. 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. 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. DROP 11. 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 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 above 14. _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. attribute 15.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 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. many 16.一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.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 inheritance 17.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 _. A. requirement analysis B. conceptual design C. logical design D. physical design 18. _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-one D. many-to-many 19.从函数依赖集F = AB，BCD，Cê，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 above 20. _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. BCNF 20. _ eliminates all redundancy that can be discovered based on functional dependencies A. 1NF B. 2NF C. 3NF D. BCNF 21.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. 3NF 21. We must ensure the property of _ in database design. A. BCNF B. lossless decomposition C. dependency preservation D. 3NF 22. _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 property of transactions. A. active B. consistency C. isolation D. durability 23. _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 manager C. concurrency control manager D. database administrator 24. _of以下指令对不冲突。 A.阅读，阅读B.阅读，写 C.写，阅读D.写，写 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。 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 one B. at least one C. at most one D. any number of 26.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S 26. 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 write 27.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_. A. S commits before T commits B. S has fewer instructions than T C. S uses less data items than T D. S enters the system before T 28.在时间戳协议，如果TS<TS，串行化顺序is_。 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 Tj B. transaction Tj appears before transaction Ti C. determined by the actual execution D. not sure 29.假设交易T22，T23，T24有时间戳5,10,15，分别。如果T22请求由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 technique is called _. A. concurrent B. starvation C. wait-die D. wound-wait 30. _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<检查点> 30. _ is not the action to take place when checkpoints are performed. A. output onto the disk all modified buffer blocks B. output onto the stable storage all log records currently residing in main memory C. perform all update actions D. output onto stable storage a log record <checkpoint> 1. A collection of interrelated data and a set of programs to access the data is called A. Database B. Database system C. File system D. DBMS 2. A major purpose of a database system is to A. enable users to access data B. provide users with an abstract view of the data C. assist users to store information D. check the constraints 相互关联的数据的1，一种收集和一组程序来访问数据被称为 A.数据库B.数据库系统C.文件系统D.数据库管理系统 2.数据库系统的一个主要目的是 A.使用户能够访问数据B.为用户提供数据的抽象视图 C.帮助用户存储信息D.检查约束 3. In database, how the data are actually stored is resolved at A. conceptual level B. view level C. logical level D. physical level 4. The collection of information stored in the database at a particular moment is called A. database instance B. database scheme C. physical scheme D. data relationship 5. A set of one or more attributes that, taken collectively, allow us to identify uniquely a tuple in the relation is called A. candidate key B. super key C. primary key D. foreign key 3.在数据库中，数据是如何实际存储在被解析 A.概念B级视图级别C.逻辑层D.物理层 4.在特定时刻存储在数据库中的信息的集合被称为 A.数据库实例B.数据库模式C.物理方案D.数据关系 5.一组中的一个或多个属性的是，采取集体，使我们确定唯一的关系的元组被称为 A.候选键B.超键C.主键D.外键 6. Physical data independence means A. application programs need not be rewritten if database schema changes B. in database, data need not to be reorganized if database schema changes C. application programs do not depend on physical database schema D. in database, logical schema must be redesigned if physical schema changes 7. Data Definition Language is used to define relational databases, includes A. define relational table, domain and user-defined types B. define consistency constraints like domain constraints, referential integrity etc. C. both A and B D. neither A nor B 8. In following terms, is proper. A. relation is a table in relational database B. attribute is a row of a table C. tuple means a column of a table D. each table must has many rows. 6物理数据独立性的手段 A.应用程序不需要，如果数据库架构更改改写 B.在数据库中，数据不需要进行重组，如果数据库架构更改 C.应用程序不依赖于物理数据库架构 D.在数据库中，逻辑模式必须的，如果物理模式的变化重新设计 7.数据定义语言来定义关系数据库，包括 A.定义关系表，域和用户定义类型 B.这样定义域约束，参照完整性等一致性约束 C. A和B D. A和B都 8.下列术语，是正确的。 答关系是在关系数据库B属性的表是一个行的表 C.元组指表D.每个表必须有许多行的一列。 9. A relation r1 may include among its attributes, a subset of attributes named as S, the primary key of another relation r2, is a correct description. A. S is a foreign key of r2 B. S is a foreign key of r1 C. r1 is referenced relation in this foreign key dependence D. S is referenced relation in this foreign key dependence 10. Stored Procedure A. is just the same as Stored Function B. is a subroutine available to applications that access a relational database system C. can be executed on database server or called by application server. D. is a transaction that must be treated as a whole. 9甲关系R1可以包括在其属性，命名为S，另一种关系r2中的主键，属性的子集是一个正确的描述。 答：A .S为R2 B. S的外键是R1的外键 C. R1被引用的关系在这个外键的依赖 D. S被引用的关系，在这个外键的依赖 10.存储过程 答：A是一样的存储函数 B.提供一个子程序访问一个关系数据库系统的应用程序 C.可以数据库服务器上执行或调用应用程序服务器。 D.是必须被视为一个整体的交易。 11. Let A, B, C and D be attributes, in the following relational algebra expressions, is not a relation. A. R(A´B´C´D) B.R(A) C. R(A,B) D. R(A,B) ´ S(C,D) 12. is not contained in the SQL language? A. Integrity B. Query execution plan C. Transaction control D. Authorization 13. Among the following sentences about trigger, is wrong. A. trigger is a special kind of stored procedure B. trigger is different to stored procedure in that it is auto-executed and with no parameters. C. triggers can be used to maintain data consistence D. in triggers, temporary table deleted and inserted can be queried and updated. 11设A，B，C和D是属性，在下面的关系代数表达式，是不是一个关系。 A. RBRC. R，D。R´S 12.不包含在SQL语言？ A.诚信B.查询执行计划C.事务控制D.授权 13.在有关触发下面的句子，是错误的。 答：触发器是一种特殊类型的存储过程 B.触发不同于存储过程中，它是自动执行，并且不带参数。 C.触发器还可以保持数据的一致性 DIN触发器，临时表中删除和插入可以查询和更新。 14. When a view is created, must be stored in data dictionary. A. the corresponding select sentence B. the definition of the view C. the data of the view D. the definition of tables used to define the view 15. In SQL, is an equivalent operator to “NOT IN” A. <>ALL B. <> SOME C. =ALL D. =SOME 16. In SQL, “CREATE INDEX” is used to create a A. relation Schema B. virtual relation C. a secondary table used to accelerate query D. database schema 当创建一个图，必须存储在数据字典。 是的。视图的对应的选择句子B中的定义 C.视图D.用来定义视图表的定义的数据 15.在SQL中，是一个等效操作员“NOT IN” A.<> ALL B.<> SOME C.= ALL D.=部分 16.在SQL中，“CREATE INDEX”用于创建一个 A.关系模式B.虚拟关系 C.辅助表用于加速查询DI。数据库模式 17. Given the following tables: Stud SC Sno Sname S# C# Grade 1 Smith 1 1 80 2 Jones 2 5 90 3 Smith 2 6 100 4 BOB 3 1 30 Which of the following statements removes the rows from the Stud table that have courses in the SC table? A. DELETE FROM Stud WHERE S# IN (SELECT Sno FROM SC); B. DELETE FROM Stud WHERE S# IN (SELECT S# FROM SC); C. DELETE FROM Stud WHERE Sno IN (SELECT S# FROM SC); D. DELETE FROM Stud WHERE Sno IN (SELECT Sno FROM SC); 18. A m:n relationship in ER model can be transferred into a relation with its primary key composed of A. primary key of re