CS403 Midterm Online Quiz

2 votes, 5 avg

CS403-Midterm

1 / 50

Making a change to the conceptual schema of a database but not affecting the existing external schemas is an example of

Logical data independence.

Physical data independence.

Functional dependency

Concurrency control.

2 / 50

Which of the following constraints enforces entity integrity?

FOREIGN KEY

PRIMARY KEY

CHECK

NOT NULL

3 / 50

statement among the following on the above diagram.

The diagram depicts existence dependencies.

The participation of Z in the Y relationship type is partial.

The relationship type Y is of cardinality ratio 1 : N.

The participation of X in the Y relationship type is total.

4 / 50

Which feature of database provides conversion from inconsistent state of DB to a consistent state ensuring
minimum data loss?

Recovery service

Data processing

Authorization service

User accessible catalog

5 / 50

Which of the following is a correct way to implement one-to-many relationship while designing tables?

by splitting each table into three

as a single table and rarely as two tables with primary and foreign key relationships

using a junction table with the keys from both the tables forming the composite primary key of the junction table.

by splitting the data into two tables with primary key and foreign key relationships

6 / 50

Which of the following is NOT a feature of Context DFD?

sub-processes (which explain and decomposed the major process into small processes)

all sources/sinks (external entities)

one process (which represents the entire system)

data flows linking the process to the sources and sinks (external entities)

7 / 50

In a conceptual model for a university, what type of relationship exists between Grade and Student entities?

1:01

Ternary

1:M

M:M

8 / 50

A ____ relationship exists when an association is maintained within a single entity.

ternary

weak

binary

unary

9 / 50

Which of the following concepts is applicable with respect to 2NF?

Any kind of dependency

Full functional dependency

Non-transitive dependency

Transitive dependency

10 / 50

Which of the following is true about relational schema?

Values are atomic.

The sequence of rows is significant.

Contains only derived attributes.

The sequence of columns is significant

11 / 50

Controlling redundancy in a database management system DOES NOT help to

avoid duplication

avoid unnecessary wastage of storage space

avoid inconsistency among data

avoid unauthorised access to data

12 / 50

Which of the following is INCORRECT statement concerning the database design process?

Transformation of the high level data model into the implementation data model is called logical design or data model mapping

During requirements collection and analysis phase, one can gather the data requirements of database users.

By referring to a high level data model, it is possible to understand the data requirements of the users, entity types, relationships and constraints

During the logical design phase of internal storage structures, access paths and file organization for the database files are specified

13 / 50

User rights information is stored in

Catalog

Physical database

Logical database

Buffer

14 / 50

Structural constraints of a relationship type refer to

the constraints applicable in granting access to tables, columns and views in a database schema.

identifying the owner entity type relevant to a given entity type

whether the existence of an entity depends on it being related to another entity via the relationship type.

the role that a participating entity from the entity type plays in each relationship instance.

15 / 50

Identify the correct statement.

Entity integrity constraints are specified on individual relations.

Entity integrity constraints are specified between weak entities.

When entity integrity rules are enforced, a tuple in one relation that refers to another relation must refer to an existing tuple.

Entity integrity constraints specify that primary key values can be composite.

16 / 50

Which of the following is true about relational schema?

The sequence of rows is significant.

Values are atomic.

The sequence of columns is significant

Contains only derived attributes.

17 / 50

Which of the following constraints enforces entity integrity?

NOT NULL

FOREIGN KEY

PRIMARY KEY

CHECK

18 / 50

Identify the correct way to implement one-to-one relationship in tables?

by splitting the data into two tables with primary key and foreign key relationships.·

by creating two separate tables

as a single table and rarely as two tables with primary and foreign key relationships.

using a junction table with the keys from both the tables forming the composite primary key of the junction table.

19 / 50

Consider the following statements.
A. Conceptual schema which is the result of conceptual design is a logical description of all data elements and their relationships.
B. Internal level of the database architecture consists of the physical view of the database.
C. External level of the database architecture provides the user view of the database.
With respect to the ANSI/SPARC three level database architecture, which of the above is/are correct?

Only A.

Only A and B.

Only C.

Only B and C.

20 / 50

Which of the following is a feature of PRIMARY KEY constraint?

unique identifier for a row within a database table.

enforces that the column will only accept null values.

allow any actions that would destroy links between tables

limit the values that can be placed in a column.

21 / 50

Select the correct statement among the following.

Role names are not technically necessary in relationship types when all the participating entity types are distinct.

Cardinality ratios for binary relationship are displayed on Entity Relationship Diagrams by using a diamond shape notation

Partial participation which is also called existence dependency is displayed as a double line connecting the participating entity type to the relationship.

When different entity types participate only once in a single relationship type it is called a recursive relationship

22 / 50

Consider the following statements.
A. An entity integrity constraint states that no primary key value can be null.
B. A referential integrity constraint is specified between two relations.
C. A foreign key cannot be used to refer to its own relation.
Identify which of the above statements is/are correct.

Only B

Only A

A and B

B and C

23 / 50

The ER- data model is an example of:

Physical database

Relational database

Conceptual database

Logical database

24 / 50

Which relational algebra operation could have been applied on the pair of relations Student and Instructor to obtain the above data?

Instructor – Student

Student ∩ Instructor

Student – Instructor

Instructor ÷ Student

25 / 50

Identify the correct statement.

Referential integrity constraints check whether the primary key values are unique.

When Referential integrity rules are enforced, a tuple in one relation that refers to another relation must refer to an existing tuple.

Referential integrity constraints check whether an attribute value lies in the given range.

Referential integrity constraints are specified between entities having recursive relationships.

26 / 50

A database system allows the following EXCEPT

more critical functions in organisations to be computerised and the need to keep a large volume of data available in an up to the minute current state increased.

management and control of data towards an efficient working of an organisation.

integration of data across multiple applications into a single application

any user to access all its data.

27 / 50

Only B

B and C

A and B

Only A

28 / 50

Which of the following statements is NOT correct?

The functional dependency EmpNo -> DeptNo holds over R.

The functional dependency (EmpNo, DeptNo) -> ProjNo holds over R.

The functional dependency ProjNo -> DeptNo holds over R.

The functional dependency (EmpNo, ProjNo) -> DeptNo holds over R.

29 / 50

Which of the following functions are NOT performed by a database administrator?

Communicating with database users

Allocation of storage locations and data structures

Establishing standards and procedures for database systems

Planning, designing and implementing database systems

30 / 50

Which of the following statements is NOT correct?

The functional dependency ProjNo -> DeptNo holds over R.

The functional dependency (EmpNo, ProjNo) -> DeptNo holds over R

The functional dependency EmpNo -> DeptNo holds over R.

The functional dependency DeptNo -> ProjNo holds over R.

31 / 50

Identify the INCORRECT statement among the given

An entity type describes the schema or intension for a set of entities which share the same structure.

An entity may be an object with a physical existence like a car, a house or an Employee.

One cannot consider something which has conceptual existence like a course in a degree program as an entity.

Age can be considered as a single value attribute of a person.

32 / 50

Database management systems, operating systems, applications and utilities are all examples of ____.

hardware

computer infrastructure

software

input and output

33 / 50

Which of the following statements is NOT correct?

The functional dependency ProjNo -> DeptNo holds over R.

The functional dependency EmpNo -> DeptNo holds over R.

The functional dependency (EmpNo, ProjNo) -> DeptNo holds over R.

The functional dependency (EmpNo, DeptNo) -> ProjNo holds over R.

34 / 50

The ____ constraint specifies whether each entity supertype occurrence must also be a member of at least one subtype.

uniqueness

completeness

inheritance

specialization

35 / 50

Which of the following is NOT a feature of Context DFD?

all sources/sinks (external entities)

► sub-processes (which explain and decomposed the major process into small processes)

data flows linking the process to the sources and sinks (external entities)

one process (which represents the entire system)

36 / 50

User rights information is stored in

Buffer

Physical database

Catalog

Logical database

37 / 50

Which of the following is INCORRECT with respect to file systems?

At the physical level, pointer or hashed address scheme may be employed to provide a certain degree of data independence at the user level.

A logical record is concerned with efficient storage of information in the secondary storage devices.

Some physical organisations use pointers to record blocks to locate records on disk.

The efficiency of a file system depends on how efficiently operations such as retrieve, insert, update, delete may be performed on the information stored in the file.

38 / 50

A software package designed to store and manage databases

Data

Database

DBMS

Data model

39 / 50

A collection of concepts that can be used to describe the structure of a database

Database

DBMS

Data model

Data

40 / 50

The ____ constraint specifies whether each entity supertype occurrence must also be a member of at least one subtype.

specialization

inheritance

completeness

uniqueness

41 / 50

A collection of related data is

Logical model

Database

Relational model

Data

42 / 50

A collection of concepts that can be used to describe the structure of a database

Database

DBMS

Data model

Data

43 / 50

Which of the following constraints enforces entity integrity?

CHECK

PRIMARY KEY

FOREIGN KEY

NOT NULL

44 / 50

As part of database naming conventions, attribute names should use suffixes such as ID, NUMBER or CODE for the _______.

determinant

index

foreign key

primary key

45 / 50

Which of the following is a correct way to implement one-to-many relationship while designing tables?

by splitting the data into two tables with primary key and foreign key relationships.

by splitting each table into three

using a junction table with the keys from both the tables forming the composite primary key of the junction table.

as a single table and rarely as two tables with primary and foreign key relationships.

46 / 50

Which of the following is true for the relational model?

Complex key is a key consisting of more than one attribute.

Degree of a relation is the number of rows in a relation.

Nullvalue is a blank or zero value given to an attribute value when its value is inapplicable or its value is unknown.

Constraint is a rule that restricts the values in a database.

47 / 50

Which of the following is not true about relational tables?

Column values are of the same kind.

The sequence of rows is significant.

Each row is unique.

Each column must have a unique name.

48 / 50

Identify the correct statement.

Entity integrity constraints are specified on individual relations.

Entity integrity constraints are specified between weak entities.

When entity integrity rules are enforced, a tuple in one relation that refers to another relation must refer to an existing tuple.

Entity integrity constraints specify that primary key values can be composite.

49 / 50

Consider the relation Interview (CandidateNo, InterviewDate, InterviewTime, StaffNo, RoomNo) and the following functional dependencies.
FD1 : CandidateNo, InterviewDate -> InterviewTime, StaffNo, RoomNo
FD2 : RoomNo, InterviewDate, InterviewTime -> StaffNo, CandidateNo
FD3 : StaffNo, InterviewDate -> RoomNo
Which of the following is correct?

The FD3 violates 3NF.

The FD2 violates 2NF.

The relation Interview is in 3NF

The relation Interview is in BCNF.

50 / 50

A relation (from the relational database model) consists of a set of tuples, which implies that

for any two tuples, the values associated with all ofheirt attributes may be the same.

all tuples in a relation must be distinct.

relational model supports multi-valued attributes whose values can be represented in sets.

all tuples in a particular relation may have different attributes.

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