CS403 Midterm Online Quiz

2 votes, 5 avg

CS403-Midterm

1 / 50

Which of the following is true for the relational model?

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

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.

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

2 / 50

Which of the following constraints enforces entity integrity?

NOT NULL

PRIMARY KEY

CHECK

FOREIGN KEY

3 / 50

Who is responsible for authorizing access to the database, for coordinating and monitoring its use?

Database Administrator

Database Designer

Application Programmer

End User

4 / 50

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

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.

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

5 / 50

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

by creating two separate tables

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

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.

6 / 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

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

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

7 / 50

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

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.

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

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

8 / 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.

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

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

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

9 / 50

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

all sources/sinks (external entities)

one process (which represents the entire system)

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

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

10 / 50

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

all sources/sinks (external entities)

one process (which represents the entire system)

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

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

11 / 50

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

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

by splitting each table into three

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

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

12 / 50

Which of the following is correct?

The relation Interview is in 3NF

The FD2 violates 2NF.

The relation Interview is in BCNF.

The FD3 violates 3NF.

13 / 50

Which of the following statements is NOT correct?

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

The functional dependency DeptNo -> ProjNo holds over R.

The functional dependency EmpNo -> DeptNo holds over R.

The functional dependency ProjNo -> DeptNo holds over R.

14 / 50

Which of the following constraints enforces entity integrity?

CHECK

NOT NULL

PRIMARY KEY

FOREIGN KEY

15 / 50

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

uniqueness

specialization

inheritance

completeness

16 / 50

Identify the constraint that limits the values that can be placed in a column.

UNIQUE

NOT NULL

CHECK

FOREIGN KEY

17 / 50

User rights information is stored in

Logical database

Catalog

Buffer

Physical database

18 / 50

Which of the following is not a benefit of normalization?

Minimize updation anomolies

Minimize deletion anomolies

Maximize redundancy

Minimize insertion anomolies

19 / 50

Which of the following is true about relational schema?

Values are atomic.

The sequence of columns is significant

The sequence of rows is significant.

Contains only derived attributes.

20 / 50

User rights information is stored in

Catalog

Physical database

Logical database

Buffer

21 / 50

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

enforces that the column will only accept null values.

unique identifier for a row within a database table.

limit the values that can be placed in a column.

allow any actions that would destroy links between tables

22 / 50

Identify the correct statement.

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 the primary key values are unique.

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

Referential integrity constraints are specified between entities having recursive relationships.

23 / 50

Which of the following statements is NOT correct?

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.

The functional dependency EmpNo -> DeptNo holds over R.

24 / 50

Which of the following is not true about relational tables?

The sequence of rows is significant.

Each row is unique.

Each column must have a unique name.

Column values are of the same kind.

25 / 50

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

Student – Instructor

Instructor – Student

Student ∩ Instructor

Instructor ÷ Student

26 / 50

Which of the following most certainly implies the need for an entire table to implement?

A ternary relationship

A recursive relationship

A binary relationship

An identifying relationship

27 / 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 A

Only B

A and B

B and C

28 / 50

Controlling redundancy in a database management system DOES NOT help to

avoid duplication

avoid unauthorised access to data

avoid inconsistency among data

avoid unnecessary wastage of storage space

29 / 50

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

Database

Data

DBMS

Data model

30 / 50

Identify the correct statement with respect to normalization.

Normalization is a formal technique that can be used only at the starting phase of the database design.

Normalization can be used as a top-down standalone database design technique.

The process of normalization through decomposition must achieve the lossless join property at any cost whereas the dependency reservation property is sometimes sacrificed.

The process of normalization through decomposition must achieve the dependency reservation property at any cost whereas the lossless join property is sometimes sacrificed.

31 / 50

Structural constraints of a relationship type refer to

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

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

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

identifying the owner entity type relevant to a given entity type

32 / 50

The ER- data model is an example of:

Logical database

Physical database

Relational database

Conceptual database

33 / 50

Which of the following is true about relational schema?

The sequence of rows is significant.

Contains only derived attributes.

The sequence of columns is significant

Values are atomic.

34 / 50

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

M:M

1:01

1:M

Ternary

35 / 50

Which of the following statements is NOT correct?

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

The functional dependency EmpNo -> DeptNo holds over R.

The functional dependency ProjNo -> DeptNo holds over R.

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

36 / 50

Identify the correct statement.

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.

Entity integrity constraints are specified between weak entities.

Entity integrity constraints are specified on individual relations.

37 / 50

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

completeness

specialization

uniqueness

inheritance

38 / 50

Which of the following is true about NOT NULL constraint?

limit the values that can be placed in a column

enforce domain integrity

prevents any actions that would destroy links between tables with the corresponding data values

enforces the uniqueness of the values in a set of columns

39 / 50

A collection of related data is

Relational model

Database

Data

Logical model

40 / 50

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

determinant

foreign key

primary key

index

41 / 50

Which of the following constraints enforces entity integrity?

CHECK

FOREIGN KEY

PRIMARY KEY

NOT NULL

42 / 50

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

Authorization service

Data processing

Recovery service

User accessible catalog

43 / 50

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

Concurrency control.

Logical data independence.

Physical data independence.

Functional dependency

44 / 50

Structural constraints of a relationship type refer to

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

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

identifying the owner entity type relevant to a given entity type

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

45 / 50

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

hardware

input and output

software

computer infrastructure

46 / 50

B and C

A and B

Only A

Only B

47 / 50

statement among the following on the above diagram.

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

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

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

The diagram depicts existence dependencies.

48 / 50

Select the correct statement among the following.

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

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

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

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

49 / 50

A software package designed to store and manage databases

Data

DBMS

Data model

Database

50 / 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 relation Interview is in BCNF.

The relation Interview is in 3NF

The FD2 violates 2NF.

The FD3 violates 3NF.

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The average score is 22%