DBW
a
A many-to-many relationship can be decomposed by three relations that have two one-to-many relationships from two relations to a intermediate relation. For improving performance based on denormalization, we can duplicate some attributes that frequently be used from _______ relation into ______ relation to reduce ______ operation. Choose one answer. a. a one-side ... the intermediate ... join b. a one-side ... the intermediate ... projection c. the intermediate ... a one-side ... projection d. the intermediate ... a one-side ... join
c
A nested relation can be represented in Object-Relational DBMS by using ________ Choose one answer. a. Recusion b. UDT (User-Defined Type) c. All of the others (row types :UDT, UDR, recusion) d. UDR (User-Defined Routine)
c
Consider the distributed query optimization, the result of Data Localization Layer is _______ Choose one answer. a. reduced query on data fragments. b. optimized relational algebra query. c. none of the others. (Each fragment is stored at site with "optimal" distribution) d. optimized execution plan.
b
Four layers of a distributed query optimization are: query decomposition, data localization, global optimization and _________ Choose one answer. a. After a participant has voted to commit a transaction, it can cannot go ahead and commit the transaction. b. Local optimization c. All of the others. d. After a participant has voted to commit a transaction, the participant may be blocked if it does not receive the global decision
c
Given below relations: Department(DepID, DepName) Instructor(InsID, FullName, DOB, Sex, DepID) , with DepID is a foreign key To display full name of female instructor that belongs to IT department. Which of the relational algebra expression below is already optimized? (note: Alias of Department is D, alias of Instructor is I) Choose one answer. a. ΠFullName (ΠDepID(σDepName='IT'(Department)) ⋈D.DepID=I.DepID ΠFullName,DepID(σSex='F'(Instructor))) b. ΠFullName (σDepName='IT'(Department) ⋈D.DepID=I.DepID σSex='F'(Instructor)) c. ΠFullName (σDepName='IT'(Department) ⋈D.DepID=I.DepID ΠFullName,DepID(σSex='F'(Instructor))) d. ΠFullName (σDepName='IT' and Sex='F' (Department ⋈D.DepID=I.DepID Instructor))
b
Given the relations below: Student(StudentID, StudentName, CampusAddress, GPA) Registration(StudentID, CourseID, Grade) Support that the following is a typical query against these relations SELECT Student.StudentID, StudentName, CourseID, Grade FROM Student, Registration WHERE Student.StudentID AND Registration.StudentID AND GPA > 3.0 ORDER BY StudentName; On what attributes should not indexes be defined to speed up this query? Choose one answer. a. StudentID of the Student relation b. None of the others c. GPA, StudentName of the Student relation d. CampusAddress
d
In a human resource management database, each staff may be has many position throughout working in the company. The end users only want to know information about the latest position of each staff. The relationship from Staff entity to Position entity should be presented as _______ in ER diagram Choose one answer. a. 1:n (one-to-many) b. 1:1 (one-to-one) c. n:n (many-to-many) d. n:1 (many-to-one)
c
In an entity-relationship model, all Library Item is separated into one of Book, Journal and Digital-Video entity types. What are participation and disjoint constraints between Library Item generalization entity and its specialization entities (i.e Book, Journal, Digital-Video) ? Choose one answer. a. mandatory (total participation) and nondisjoint (overlapping) b. optional (partial participation) and nodisjoint (overlapping) c. mandatory (total participation) and disjoint d. optional (partial participation) and disjoint
d
In entity-relationship diagram, the multiplicity identifies ________ Choose one answer. a. None of the others b. the number of key atributes of a entity. c. the number of participating entity type in a relationship. d. the number of possible occurrences of an entity type in a relationship.
c
Most Data Manipulation Languages lacked computational completeness. To overcome this problem and to provide additional flexibility, the SQL standard be extended and allows SQL statements can be embedded in a high-level Third-generation programming language. However, this approach produces a( n ) ________ because of mixing between different programming paradigms. This is a weakness of relational model. Choose one answer. a. type mismatch b. invalid type c. impedance mismatch d. semantically overloaded
a
Object-Relational DBMS, by using row type, we can represent for a ________ attribute directly Choose one answer. a. composite b. simple c. all of the others d. derived
c
Select INCORRECT meaning about the objective of local-autonomy feature in the Date's twelve rules for a distributed DBMS Choose one answer. a. local data is locally owned and managed b. none of the others. c. all operations at a given site are controlled by the centralized site d. local operations remain purely local
a
Select INCORRECT statement about CORBA (The Common Object Request Broker Architecture) Choose one answer. a. The COBRA is first Object-Oriented Programming Language b. The CORBA enables separate pieces of software written in different languages and running on different computers to work with each other like a single application or set of services. c. The CORBA uses an interface definition language (IDL) to specify the interfaces which objects present to the outer world. d. The CORBA is a standard defined by the Object Management Group (OMG) that enables software components written in multiple computer languages and running on multiple computers to work together.
a
Select INCORRECT statement about OMG - Object Management Group Choose one answer. a. The primary aims of OMG are promotion of object-oriented approach and Development of standards in which location, environment, language, and other characteristics of objects are completely transparent to other objects. b. The OMG is not a recognized standard group unlike the ISO - International Organization for Standardization. c. None of the others d. The OMG is a international nonprofit-making industry consortium founded in 1989 to address the issues of object standards.
None of the other
Select correct statement Choose one answer. (?? Cau nao cung sai) a. A distributed database is also a data warehouse. b. A distributed database is a collection of multiple, logically interrelated databases distributed over a computer network. c. A distributed DBMS is a DBMS running across multiple processors and disks that is designed to execute operations in parallel whenever possible. (parallel DBMS) d. All of the others
c
Select correct statement about the set built-in collection type Choose one answer. a. a set is an ordered collections that do not allow duplicates b. a set is an unordered collections that do allow duplicates c. a set is an unordered collections that do not allow duplicates d. a set is an ordered collections that do allow duplicates
a
Select incorrect statement Choose one answer. a. None of the others. b. Vertical fragment can be defined by using projection operation of relational algebra. c. Mixed fragment can be defined by using selection and projection operations of relational algebra. d. Horizontal fragment can be defined by using selection operation of relational algebra.
b
Select incorrect statement Choose one answer. a. Heterogeneous systems usually result when individual sites have implemented their own databases and integration is considered at a later stage. b. Heterogeneous Distributed DBMS is a system where all sites use the same DBMS product. c. All of the others. d. Designing and managing a homogeneous system is much easier than heterogeneous system.
c
Select incorrect statement Choose one answer. (?? What is better? Time, cost, data) a. Two methods for executing the query optimization are dynamic query optimization and static query optimization. b. Static query optimization method does not need the database statistics. c. The static query optimization method is better than the dynamic query optimization method. d. The dynamic query optimization method is better than the static query optimization method.
a
Select incorrect statement about creating an index. Choose one answer. a. Create index on the attributes that is frequently updated b. Create index on the attributes that are frequently involved in condition of join operation c. Create index on the foreign key if it is frequently accessed. d. Create a index on primary key.
a
Select incorrect statement about reference type of object-relational database model Choose one answer. a. None of the others b. Reference type gives the optimizer an alternative way to navigate data instead of using value-based joins. c. Reference type allows a row to be shared among multiple tables. d. Reference type enables users to replace complex join definitions in queries with much simpler path expressions.
d
Select incorrect statement about the creating directed edge in precedence graph. Choose one answer. a. create a directed edge Ti -> Tj, if Tj writes a value into an item after it has been read by Ti b. create a directed edge Ti -> Tj, if Tj reads the value of an item be written by Ti c. create a directed edge Ti -> Tj, if Tj writes a value into an item after it has been written by Ti d. create a directed edge Ti -> Tj, if Tj reads the value of an item be read by Ti
c
Select incorrect statement about the translation process from ER diagram, containing weak entities, to relational model Choose one answer. (đề sai?? All of the others?) a. The key of a relation corresponding to a weak entity does not include key of the owner entity. b. For each weak entity in ER diagram, create a relation that includes all attributes of that weak entity. c. None of the others. d. Create only one relation corresponding to a weak entity and the owner entity of it
c
Student(StudentID, StudentName, CampusAddress, GPA) Registration(StudentID, CourseID, Grade) Support that the following is a typical query against these relations SELECT Student.StudentID, StudentName, CourseID, Grade FROM Student, Registration WHERE Student.StudentID AND Registration.StudentID AND GPA > 3.0 ORDER BY StudentName; On what attributes should not indexes be defined to speed up this query? Choose one answer. a. GPA, StudentName of the Student relation b. StudentID of the Student relation c. None of the others d. StudentID, CourseID of the Registration relation
c
The encapsulation feature in Object-Relational database model is presented by _______ Choose one answer. (chap 29) a. all of the others b. persistent stored module. (use in stored procedures) c. observer and mutator functions of user-defined type (giống getter và setter). d. user-defined supertype and subtype (inheritance).
d
The inputs of physical database design are the logical data model and the _______. The outputs are the ______, integrity rules, file organization specified, secondary indexes determined, user views and access rules Choose one answer. a. data dictionary ... general constraints b. business logic ... data dictionary c. business logic ... base relations d. data dictionary ... base relations
d
The major components of the Object Data Management Group (ODMG) architecture for an Object-Oriented DBMS are: Object Model (OM), ________, Object Query Language (OQL) and C++, Smalltalk, and Java Language Binding. Choose one answer. a. Common Object Request Broker Architecture (CORBA) b. Interface Definition Language (IDL) c. None of the others d. Object Definition Language (ODL)
a
There are two mechanisms to propagate updates in replication environment. With _____ replication, the replicated data is updated immediately when the source data is updated. An alternative mechanism is called _____ replication.With this mechanism, the replicated data is updated after the source database has been modified. Choose one answer. a. synchronous ... asynchronous b. master ... slave c. publisher ... subscribers d. update-anywhere ... read-only
b
Three generally techniques for handling deadlock are : timeout, deadlock prevention, and deadlock detection. The deadlock prevention approach uses ______ or conservative 2PL to prevent deadlock. While the deadlock detection approach uses _____ that shows the transaction dependencies to detect deadlock. Choose one answer. a. transaction timestamp ... precedence graph b. transaction timestamp ... wait-for graph c. strict-2PL ... precedence graph d. strict-2PL ... wait-for graph
c
To convert ER data model to relational data model. For each many-to-many (*:*) binary relationship, we create a relation to represent the relationship and post a copy of the ________ attribute(s) of the entities that participate in the relationship into this relation, to act as ________. Choose one answer. a. primary key ... foreign keys b. primary key ... alternate key c. primary key ... unique key d. foreign keys ... primary key
b
Using Embedded SQL, a programmer is responsible for writing explicit code to fetch data into memory or store data back to the database. But when a __________ be used, a programmer can manipulate persistent data without having to write such code explicitly. Choose one answer. a. Object Query Language b. Persistent Programming Language c. Functional Query Language d. Persistent Stored Module (SQL/PSM)
b
When an ER diagram are transformed into relations. For each multi-valued attribute in an entity, create a new relation to represent the multi-valued attribute and include the _______ of the entity in the new relation, to act as a foreign key. The primary key of this new relation consists of two attributes: the primary key of the original relation, plus the ______ attribute itself. Choose one answer. a. primary key ... foreign key b. primary key ... unique key c. primary key ... multi-valued d. multi-valued ... foreign key
a
When an ER diagram are transformed into relations. For each one-to-many (1:*) binary relationship type, one relation is created for each of the two entity types participating in the relationship. The ______ attribute of the entity on the one-side of the relationship becomes a ______ in the relation on the many-side of the relationship Choose one answer. a. primary key ... foreign key b. primary key ... primary key c. foreign key ... primary key d. primary key ... unique key
a (primary index = clustering index, secondary index = non-clustering index)
When the ordering attribute (index field) chosen is the key attributes of the relation, the index will be a _______; when the ordering attribute (index field) is the non-key attributes, the index will be a _______. Each relation can only have either a primary index or a clustering index and several secondary indexes. Choose one answer. a. clustering index ... secondary index b. clustering index ... primary index c. primary index ... clustering index d. primary index ... secondary index
c
Which information does the physical database design phase provide ? Choose one answer. a. Definitions of each attribute, along with physical specifications such as maximum possible length. b. Descriptions of where and when data are used in various ways (entered, retrieved, deleted, and updated, including typical frequencies of these events). c. All of the others. d. All base relations, including estimates for the range of the number of rows in each table.
a
Which of following statement is not correct ? Choose one answer. a. A subtype (subclass) is a subgrouping of the entities in an entity type that is meaningful to the organization. b. A supertype (superclass) is a generic entity type that has a relationship with one or more subtypes (subclasses). c. The specialization is a process of defining one or more superclasses of the subclass, and forming the relationships between the superclasses and subclasses. d. All of the others.
c
Which of following statement is not correct ? Choose one answer. a. None of the others. b. Disjoint constraint specifies that if an entity instance (of the superclass) is a member of one subclass, it cannot simultaneously be a member of two (or more) subclasses. c. Mandatory participation constraint specifies that each entity instance of the superclass may not be a member of some subclass in the relationship. d. Overlap (nondisjoint) constraint specifies that an entity instance can simultaneously be a member of two (or more) subclasses.
a (denomolization (parsing, validating), optimizing, code generation and executing)
Which of following statement is not correct? Choose one answer. a. Query processing is the activities involved in parsing, validating, optimizing, and executing a query. b. None of the others. c. The aims of query processing are to transform a query into a correct and efficient execution strategy, and to execute the strategy to retrieve the required data. d. The best optimized query is a query that returns the smallest number of tuples.
d
Which of following transformation rules is NOT correct ? Choose one answer. a. πA1, A2,..., An (σ p(R)) = σ p (πA1, A2,..., An (R)) , where the selection predicate p involves only the attributes A1, A2,..., An b. σp (σq (R)) = σq (σp (R)) c. σ p ⋎ q ⋎ r (R) = σp (σq (σr (R))) d. None of the others.
b
Which of the following about transaction is NOT correct ? Choose one answer. a. When transaction is aborted, all effects of the transaction on the data must be rolled back. b. After a transaction has been committed, all effects of the transaction on the data can be rolled back. c. All of the others. d. After a transaction has been committed, all effects of the transaction on the data should be permanently recorded in the database.
a
Which of the following is not a object-oriented feature that being added in ORDBMS ? Choose one answer. a. interface b. polymorphism c. inheritance d. encapsulation
a
Which of the following situations can NOT be applied the denormalization to improve data retrieval? Choose one answer. a. Duplicating key attributes in one-to-many (1:*) relationships to simplify join-predicate. b. Duplicating attributes in many-to-many (*:*) relationships to reduce join operations c. Combining one-to-one (1:1) relationships. d. Duplicating non-key or foreign key attributes in one-to-many (1:*) relationships to reduce join operations
a
Which of the following statements is NOT correct about 2-PL protocol? Choose one answer. a. Shrinking and growing are phases in 2-PL protocol. Shrinking is the first phase, and growing is the second phase. b. In growing-phase, a transaction acquires all the locks needed but cannot release any locks. c. In shrinking-phase, a transaction releases its locks but cannot acquire any new locks d. A transaction follows the two-phase locking protocol if all locking operations precede the first unlock operation in the transaction.
b
Which of the followings is not a benefit of database replication in a distributed system ? Choose one answer. a. increase availability b. none of the others. c. support a disconnected computing model d. increase performance of the system
a
Which of the followings is not an advantage of centralized 2PL in a distributed environment Choose one answer. a. Bottleneck issue may be occur at the site that maintains the locking information b. Easy to implement. c. None of the others. d. Deadlock detection is no more difficult than centralized DBMS.
d
Which of the implementation methods for replication ensures atomicity feature of an transaction ? Choose one answer. a. Snapshot update b. All of the others c. Database trigger d. Transactional update
b
Which one is not a reason for needing to design database at conceptual level ? Choose one answer. a. Allows for easy converting from high-level model to relational model b. Allows for easy communication between end-users and developers c. Independent of DBMS d. None of the others
c
Why conceptual design phase should not be ignored in the designing database for enterprise application ? Choose one answer. a. It uses entity-relationship diagram. b. It identifies the most important relations and their attributes. c. All of the others. d. It identifies what data be used in an enterprise, and entirely independent of implementation details.
c
With UML, a _______ model the functionality provided by the system, users who interact with system, and association between the users and the functionality. Choose one answer. a. activity diagram b. class diagram c. use-case diagram d. collaboration diagram
b
_________ is a language that provides the programmer with the ability transparently to preserve data across successive executions of a program, and even allows such data to be used by different programs. Choose one answer. a. Object-Oriented Programming Language b. Persistent Programming Language c. Persistent Stored Module (SQL/PSM). d. Functional Programming Language