CS403 Midterm Online Quiz

2 votes, 5 avg

CS403-Midterm

1 / 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 particular relation may have different attributes.

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

all tuples in a relation must be distinct.

2 / 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 3NF

The relation Interview is in BCNF.

The FD2 violates 2NF.

The FD3 violates 3NF.

3 / 50

Which of the following is true about relational schema?

The sequence of columns is significant

The sequence of rows is significant.

Contains only derived attributes.

Values are atomic.

4 / 50

Which of the following is correct?

The FD3 violates 3NF.

The FD2 violates 2NF.

The relation Interview is in BCNF.

The relation Interview is in 3NF

5 / 50

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

Recovery service

Data processing

User accessible catalog

Authorization service

6 / 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

7 / 50

Structural constraints of a relationship type refer to

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

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

8 / 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.

limit the values that can be placed in a column.

allow any actions that would destroy links between tables

9 / 50

Select the correct statement about the ANSI/SPARC architecture.

The external level is not concerned with individual user perceptions, while the conceptual level is concerned with a community user perception.

The conceptual level is a level of indication between the internal level and the external level.

Any given database has many conceptual schemas and one physical schema, but it has only one external schemas.

The internal level in a database system will definitely be relational.

10 / 50

Which of the following constraints enforces entity integrity?

FOREIGN KEY

PRIMARY KEY

CHECK

NOT NULL

11 / 50

Controlling redundancy in a database management system DOES NOT help to

avoid unauthorised access to data

avoid unnecessary wastage of storage space

avoid inconsistency among data

avoid duplication

12 / 50

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

Any kind of dependency

Non-transitive dependency

Full functional dependency

Transitive dependency

13 / 50

Which of the following constraints enforces entity integrity?

PRIMARY KEY

NOT NULL

FOREIGN KEY

CHECK

14 / 50

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

unary

ternary

weak

binary

15 / 50

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

A ternary relationship

A binary relationship

An identifying relationship

A recursive relationship

16 / 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.

Concurrency control.

Physical data independence.

Functional dependency

17 / 50

Which of the following statements is NOT correct?

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.

The functional dependency ProjNo -> DeptNo holds over R.

18 / 50

Which of the following is true about relational schema?

Values are atomic.

The sequence of columns is significant

Contains only derived attributes.

The sequence of rows is significant.

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 C.

Only A and B.

Only A.

Only B and C.

20 / 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

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.

21 / 50

Which of the following is true for the relational model?

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

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

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

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

22 / 50

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

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.

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

23 / 50

User rights information is stored in

Logical database

Catalog

Physical database

Buffer

24 / 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.

B and C

Only A

Only B

A and B

25 / 50

Which of the following enforces a relation into 1st normal form?

Every non-key attribute is partially dependent on super key

non-key attribute is non-transitively dependent on primary key.

Every non-key attribute is fully functionally dependent on primary key

The domain of attribute must include only atomic values.

26 / 50

The ER- data model is an example of:

Physical database

Logical database

Relational database

Conceptual database

27 / 50

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

Database

Data model

Data

DBMS

28 / 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.

any user to access all its data.

integration of data across multiple applications into a single application

29 / 50

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

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.·

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

by creating two separate tables

30 / 50

Identify the correct statement with respect to normalization.

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

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 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.

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.

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

32 / 50

statement among the following on the above diagram.

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

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

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

The diagram depicts existence dependencies.

33 / 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 (EmpNo, ProjNo) -> DeptNo holds over R.

The functional dependency ProjNo -> DeptNo holds over R.

34 / 50

Identify the correct statement.

Entity integrity constraints are specified between weak entities.

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

Entity integrity constraints are specified on individual relations.

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

35 / 50

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

one process (which represents the entire system)

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

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

all sources/sinks (external entities)

36 / 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.

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

by splitting each table into three

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

37 / 50

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

1:01

Ternary

M:M

1:M

38 / 50

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

completeness

uniqueness

inheritance

specialization

39 / 50

Which of the following constraints enforces entity integrity?

CHECK

FOREIGN KEY

NOT NULL

PRIMARY KEY

40 / 50

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

software

hardware

computer infrastructure

input and output

41 / 50

A collection of related data is

Data

Logical model

Relational model

Database

42 / 50

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

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

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

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

43 / 50

The ER- data model is an example of:

Physical database

Logical database

Conceptual database

Relational database

44 / 50

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

all sources/sinks (external entities)

one process (which represents the entire system)

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

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

45 / 50

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

Communicating with database users

Planning, designing and implementing database systems

Establishing standards and procedures for database systems

Allocation of storage locations and data structures

46 / 50

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

DBMS

Database

Data

Data model

47 / 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 an attribute value lies in the given range.

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

Referential integrity constraints are specified between entities having recursive relationships.

48 / 50

Identify the correct statement.

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.

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

49 / 50

Which of the following is true about NOT NULL constraint?

enforce domain integrity

enforces the uniqueness of the values in a set of columns

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

limit the values that can be placed in a column

50 / 50

Which of the following is not a benefit of normalization?

Minimize updation anomolies

Minimize insertion anomolies

Maximize redundancy

Minimize deletion anomolies

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