数据库复习题54220

1、Chapter 12A.For each of the following questions there are four choices marked A, B, C and D. Only one of them is correct. You should decide on the correct choice and write down its mark on the answer sheet.1We can identify five major components in the DBMS environment. They are hardware, software, p

2、rocedures, people and .Adatabase BDBMS CdataDDBS2The relationship among DB, DB application and DBS is .AA DB system contains multiple DB applications, which access DBBA DB application contains only one DB system, which accesses DBCA DB contains multiple DB applications, which access DB systemDA DB a

3、pplication contains multiple DBs, which access DB system3The most appropriate method to manage data with high data sharing and low data redundancy is .Afile-based approach Bentity-relationship approachCdata-driven approachDdatabase approach4In the following properties, the one that does not belong t

4、o database approach is .Ahigh data sharing Bimproved data integrityChigh data redundancyDimproved data independence5In database systems, data independence means that .Athe immunity of application programs to changes of the data valueBthe immunity of application programs to changes of the data amount

5、sCthe immunity of application programs to changes of the data structureDthe immunity of the data storage structure to changes of the data storage approach6The person who manages the data resource involved in DB is referred to as .ADBA BEMBA CMBA DDA7The person who is responsible for the physical rea

6、lization of the database is referred to as .ADBA BEMBA CMBA DDA8 contains the global logical representation of the entire database.AConceptual schemaBInternal schemaCExternal schemaDPhysical schema9It is that ensures the data independence in database system.Athe schema and the external schemaBthe sc

7、hema and the internal schemaCthe two mappings between the three level of schemasDthe three level of schemas10It is that ensures the logical data independence in database system.Athe mappings between conceptual schema and external schemasBthe mapping between conceptual schema and internal schemaCthe

8、conceptual schemaDthe three level of schemas11The description of the database logical structure that can be seen by both users and application programs is called .Aconceptual schemaBinternal schemaCexternal schemaDphysical schema12Which of the following tasks is not a duty of DBA ?.Adefining integri

9、ty constraintsBdefining database schemaCmanaging database securityDdesigning database management system13Which of the following operations is not supported by DML ?Ainserting some rows into a tableBdeleting some rows from a tableCfinding some rows from a tableDcreating some tables in a database14Whi

10、ch of the following operations is not supported by DDL ?Acreating some views in a databaseBmodifying table structures in a databaseCfinding some rows from a tableDcreating some tables in a database15Among object-based data models, the most famous one is .Aentity-relationship data modelBsemantic data

11、 modelCrelational data modelDfunctional data model16A data model comprises three components, they are .Athe external schema, the conceptual schema and the internal schemaBthe relations, the tuples and the primary keysCthe structural part, the manipulative partand the integrity rulesDthe meaning of m

12、odel, the operational rules and the implementation language17The data in a hierarchical data model is of .Aa tree structureBa directed graph structureCa linear structure Da tabular structure18The data in a network data model is of .Aa tree structureBa directed graph structureCa linear structure Da t

13、abular structure19A relational data model is the most important model that is composed of .Athe relational data structure, the relational operations and the integrity constraintsBthe relations, the tuples and the primary keysCthe entity integrity, the referential integrity and the user-defined integ

14、rityDthe external schema, the conceptual schema and the internal schema20If we query in a database based on a , we need only to express what and not how.Ahierarchical data modelBnetwork data modelCrelational data model Dphysical data model21Which of the following is true in database systems?ADBMS ru

15、ns concurrently with OS.BDBMS and OS call each other.COS calls DBMS. DDBMS calls OS.22In designing file-based systems, as the main problem is the design of system functions, among the following works, the most important one is .Adesigning data structureBprogrammingCmemory arrangementDinformation sto

16、rage23The core of the information processing based on database systems is .Athe diskBprogramCthe dataDthe memory24In database system, the conversion between logical data and physical data can be done by .Aapplication programsBthe OSCthe DBMSDI/O facilities25There is among the three-level schemas of

17、a database system.AintegrityBconsistencyCstructural consistencyDa great difference26The three-level architecture of database systems is the three-level abstractions for .AmemoriesBdataCprogramsDdisks27Among the three-level schemas of database systems, the nearest one from the secondary storage is .A

18、the external schemasBthe conceptual schemaCthe subschemasDthe internal schema28It is just because that there is data independence in database systems.Athe disk-based storageBthe three-level schemasCthe data access by calling OSDthe visualized programming language29In database systems, the relation b

19、etween data independence and data relationship is that .Athey are irrelevant conceptsBthey are simultaneously true or falseCthe former infers the latterDthey can infer each other30In database system, data independence means that .Athis data is independent on that dataBapplication programs are indepe

20、ndent on the database structureCdisk is independent on memoryDdata is independent on diskB. Fill in blanks with proper words or phrases1Database refers to a (a) collection of (b) data, and the (c) of this data, designed to meet the information needs of an organization.2An entity is a (a) that is to

21、be represented in the database; an attribute is a (b) of an entity; a relationship is an (c) between entities3We can identify five major components in the DBMS environment. They are (a) , (b) , (c) , (d) and (e) .4DBMS refers to a software system that enables users to (a) , (b) , and (c) the databas

22、e, and that provides (d) to this database.5Typically, DBMS provides the following facilities: (a) , (b) , (c) and (d) .6.The controlled access to database of DBMS may include: (a) , (b) , (c) , (d) and (e) .7.The three-level schema architecture of database includes: (a) , (b) , (c) , where there may

23、 be multiple (d) in a database, but there are only one (e) and (f) in a database.8.Roles in the database environment include: (a) , (b) , (c) , (d) and (e) .9.A conceptual schema of database contains a (a) of the entire database, which includes: all entities, their (b) , and their (c) ; (d) on data;

24、 semantic information about data; (e) and (f) information.10.Logical data independence refers to the immunity of (a) to changes in (b) . That is: changes in (c) do not require to modify (d) and (e) . This is guaranteed by (f) mappings.11.Physical data independence refers to the immunity of (a) to ch

25、anges in (b) . That is: changes in (c) do not require to modify (d) . This is guaranteed by (e) mapping.12.Data model refers to an integrated collection of concepts for describing (a) , (b) , and (c) . A data model comprises three components: (d) , (e) and (f) .13.Categorized by the abstract levels

26、of data, there are 3 categories of data models, they are: (a) , (b) and (c) .14.Object-based data models include (a) , (b) , (c) and (d) .15.Record-based data models include (a) , (b) and (c) .16.Multi-user DBMS architectures include (a) , (b) and (c) .Chapter 34A.For each of the following questions

27、 there are four choices marked A, B, C and D. Only one of them is correct. You should decide on the correct choice and write down its mark on the answer sheet.1Which one of the following is not the property of relations?AEach attribute has a distinct data type. BEach attribute has a distinct name.CO

28、rder of rows has no significance.DOrder of cols has no significance.2In relational models, each relation can only have one .Acandidate key Bforeign key Cinner keyDprimary key3In relational models, each candidate key .Acan only have at least two attributesBcan only have at most one attributesCmay hav

29、e one or more attributesDmust contain all the attributes of the relation4Given a relation schema R and its attributes X, if X references a candidate key Y of relation schema S, then we call .AX is a foreign key of relation schema SBY is a foreign key of relation schema RCX is a foreign key of relati

30、on schema RDY is a foreign key of relation schema S5Suppose Set D1, D2 and D3 have K1, K2 and K3 elements, respectively, then the number of tuples in D1D2D3 will be _.AK1 K2 K3BK1+ K2+ K3C(K1+ K2)K3D(K1+ K2)K36Special relational operations that a relational DBMS should support include: .Asorting, in

31、dexing and statistical operation Bselection, projection and joinCassociation, update and sortingDdisplay, print, tabulation 7Between relation schema and relational database schema, which of the following is true?ARelation schema is a type, relational database schema is its value.BRelational database

32、 schema is a type, relation schema is its value.CRelation schema is a set of relational database schemas.DRelational database schema is a set of relation schemas.8Between relation and relation schema, which of the following is true?ARelation schema is a type, relation is its value.BRelation is a typ

33、e, relation schema is its value.CRelation schema is a set of relations.DRelation is a set of relation schemas.9Between relational database and relational database schema, which of the following is true?ARelational database is a type, relational database schema is its value.BRelational database schem

34、a is a type, relational database is its value.CRelational database schema is a set of relational databases.DRelational database is a set of relational database schemas.10Between relation and relational database, which of the following is true?ARelational database is a type, relation is its value.BRe

35、lation is a type, relational database is its value.CRelational database is a set of relations.DRelation is a set of relational databases.11Null represents a value for an attribute in a tuple that is .AzeroBan empty setCa spaceDcurrently unknown or not applicable12Relation schema is .Athe association

36、 schema between two relationsBthe association schema between a relation and a tupleCthe description of a relationDthe description of the relationship between two relations13.If F is a foreign key of relation R that targets a candidate key K of relation S, then F can only take .Anull valuesBnull valu

37、es or values that appear in KCvalues that appear in KDvalues that appear in R14Relational integrity means .Athe correctness and consistency of data in relationsBthat every relation must integrally contain all the possible dataCthat every data must be integrally represented in relationsDthat we must

38、integrally describe specific problems using relations15In relational model, entity integrity means that .Athere must not be empty rows in every relationBno attribute of a primary key can be nullCattributes are allowed to be nullDforeign keys are allowed to be null16The main property of relational op

39、erations in relational algebra is that .Aboth the operational objects and the result are fieldsBthe operational objects are fields, but the result is a relationCthe operational objects are relations, but the result is a fieldDboth the operational objects and the result are relations17Suppose R and S

40、 are n-ary relations with the same attribute set, then the difference of R and S, denoted as , is composed of tuples that belong to R but not to S.ARSBSRCRSDSS 18The projection operation in relational database refers to a relation.Athe extraction of specific records fromB. the extraction of specific

41、 fields fromCthe creation of specific images of D. the creation of specific graphs of19Which of the following operations can extract from a relation all records that satisfy a condition to form a new relation?AProjection BJoinCSelectionDDivision20In general, to conduct natural join between relation

42、R and S, it is necessary for R and S to possess common . ArecordsBrowsCattributesDtuples21The degree of a relation refers to in the relation.Athe number of rowsBthe number of tuplesCthe number of candidate keysDthe number of columns22Suppose there are 10 tuples in each of relation R, S and W, then t

43、he number of tuples in RSW is .A10B30C1000Dunknown23Suppose there are respectively 2 and 3 attributes in relation R and S, then RS is equivalent to .As12(RS)Bs14(RS)Cs12(RS)Ds14(RS)24If there is no common attributes in two relations, then the natural join between them is equivalent to .ACartesian pr

44、oductBequi-joinCq-joinDouter join25Which of the following equations is wrong?AR-S = R (RS)BR = (R-S)(RS)CRS = S-(S-R)DRS = S-(R-S)26Suppose we are given relation R(A,B,C) and S(B,C,D), then which of the following relational algebra expressions is equivalent to RS ?As3=5(RS)BP1, 2, 3, 6(s3=5(RS)Cs3=5

45、2=4(RS)DP1, 2, 3, 6(s3=22=1(RS)27Suppose we are given relation R(A,B,C) and S(B,C,D), then which of the following relational algebra expressions is equivalent to RS ?As3=5(RS)BP1, 2, 3, 6(s3=52=4(RS)Cs3=52=4(RS)DP1, 2, 3, 6(s3=22=1(RS)28Suppose we are given relation R(A,B,C) and S(B,C), then which o

46、f the following relational algebra expressions is equivalent to RS?Aa | aA(R) B ( A=a(R) ) B (S) Ba | aA(R) B,C ( A=a(R) ) S Cb | bB(S) B ( B=b(S) ) B (R) Db | bB(S) B=b(S) B,C (R) B. Fill in blanks with proper words or phrases1In relational model, a table with columns and rows is called a (a) ; a r

47、ow in the table is called a (b) ; a named column of the table is called an (c) ; the set of allowable values for named columns of the table is called a (d) ; the number of columns in a table is called the (e) of the table; the number of rows in a table is called the (f) of the table.2Suppose there a

48、re 2, 3 and 4 tuples in Set D1, D2 and D3, respectively, then there are (a) tuples in D1D2D3, each of which has (b) components.3In relational model, the properties of base relations are: 1) relation name is (a) all other relation names in the relational database schema; 2) each cell of a relation co

49、ntains (b) ; 3) each attribute has a (c) name; 4) values of an attribute are all from (d) domain; 5) each tuple is (e) ; 6) order of attributes has (f) ; 7) order of tuples has (g) .4Relational keys refer to attributes that (a) each tuple in a relation. There are 5 kinds of relational keys: 1) (b) ;

50、 2) (c) ; 3) (d) ; 4) (e) ; 5) (f) .5An attribute, or a set of attributes that (a) each tuple in a relation is called a superkey; a candidate key is a superkey such that (b) of the superkey is a superkey; a primary key is a (c) that is selected to uniquely identify tuples in a relation; alternate ke

51、ys are (d) that are not selected to be primary key; a foreign key is an attribute, or a set of attributes within one relation that (e) of some (possibly same) relation.6Suppose we are given relation Student(, CID, ) and Class(ClassID, ), if CID matches the primary key of Class, then we say (a) is a

52、foreign key of (b) that targets relation (c) .7.Entity integrity rule stipulates that in a base relation, no (a) of a (b) can be (c) .8.Referential integrity rule stipulates that if F is a (a) of relation R that targets a (b) K of relation S, then F can only take (c) values or values that (d) K9. In

53、 relational algebra, special relational operations include (a) , (b) , (c) and (d) .10.Suppose R and S are n-ary relations with the same attribute set, then: operation (a) can find all tuples that appear in both R and S; operation (b) can find all tuples that appear in R or S; operation (c) can find

54、 all tuples that appear only in R but not in S.11.Suppose we are given a relation R(A,B,C) =(1,10,50), (2,10,60), (3,20,72), (4,30,60)，then the number of tuples in the result of B(sC70(R) will be (a) , and each tuple in the result has (b) component.12. Suppose we are given relation Student(Sno CHAR(

55、5), Sname CHAR(10) ), SC( Sno CHAR(5), Cno CHAR(5), Grade FLOAT) and Course(Cno CHAR(5), Cname CHAR(40) ), where a row in Student means that a student with student number Sno has student name Sname, a row in SC means that a student with student number Sno takes part in a course with course number Cno an