WorksheetsDBMS query optimization
Total questions: 81
Worksheet time: 40mins
Which is NOT an advantage of using a database.
Storage space is reduced.
Accessing data is slow and inefficient.
Easy to access data.
Easy to edit.
What is a Database?
A music band.
A new type of technology.
An organised collection of data.
Computer code.
DBMS stands for what
Database Management System
Database Master System
Database Management Structure
None of the above
The database is an organized collection of related………
Data
Modules
Programs
None of the above
Before use of DBMS information was stored using __________.
Cloud Storage
Data System
File Management System
None of the above
The DBMS is the software that interacts with the ……………….and the database.
system programs
application programs
system database
None of the above
An advantage of the database management approach is
Data is dependent on programs
Data redundancy increases
Data is integrated and can be accessed by multiple programs
None of the above
Which of the following is not an advantage of DBMS?
Improved data integrity
Increased concurrency
Complexity and Size
Improved backup
The way a particular application views the data from the database that the application uses is
Module
Relational model
Schema
Sub Schema
A software system that enables users to define, create, maintain, and control access to the database.
Database Management System
Data Management
Filing system
Record
Candidate Key is a specific type of field in a relational database that can identify
each record uniquely.
each attribute uniquely.
each table in a database.
each column of a table.
Consider relations R and S. A natural join is the set of tuples of all combinations in R and S that are equal on their common attribute names.
TRUE
FALSE
A data model determines
the structure of hardware components.
the structure of a computer.
the structure of software components.
the structure of data.
The database architecture focuses on the design and implementation of computer programs that store and organize
information for a computer.
information for a business.
information of all device in a computer.
information about the parts of a computer.
Data redundancy
always lead to data inconsistency.
sometimes lead to data inconsistency.
means data inconsistency.
is not related to data inconsistency.
Consider relations R and S. A natural join is the set of tuples of all combinations in R and S that are equal on their common attribute names.
TRUE
FALSE
Normalization is used to eliminate
Insertion and Deletion Anomalies
Deletion and Update Anomalies
Update Anomalies.
Insertion, Deletion and Update Anomalies
If there is no transitive dependency for non-prime attributes, then the relation must be in
Second Normal Form.
Third Normal Form.
First Normal Form
Fourth Normal Form.
A relation will be in 4NF if it is in Boyce-Codd normal form and has no
Functional dependency.
Transitive dependency.
Multi-valued dependency.
Join dependency.
Data redundancy occurs
when the same piece of data exists in multiple places.
when there is mismatch of data.
when there is NULL values.
when there is multiple values for an attribute.
The design of a DBMS
depends on its ER diagram.
depends on its architecture.
depends on its Entity set.
depends on its attributes.
A data schema is a formal
description of relations.
description of database.
description of data.
description of tuples.
A key that can be uniquely used to identify a database record, that may contain extra attributes that are not necessary to uniquely identify records.
Foreign key.
Primary key.
Candidate key.
Super key.
Database transactions intended to guarantee data validity
despite errors or power failures.
despite data mismatch.
despite data redundancy.
despite data inconsistency.
Normalization of a Database is achieved by following a set of rules called 'forms' in creating the database.
TRUE.
FALSE.
Functional dependency X→Y.
It is denoted by X→Y.
X is called the determinant.
Y depends upon X.
All of them.
If there is only one candidate key then the 3NF and BCNF are identical .
TRUE.
FALSE.
A relation decomposed into two relations must have loss-less join Property, which ensures that no spurious or extra tuples are generated
when tuples are reunited.
when a transaction is carried out.
when relations are decomposed.
when relations are reunited through a natural join
What is DBMS stands for
Database Manager Service
Database Management System
Database Manipulation Service
Data Business Management Service
Data inconsistency is different and conflicting version of same data occurs at different place
TRUE
FALSE
A database architect develops and implements software to meet the needs of
customer
computer
user
programmer
Primary Key is a minimal set of attributes that uniquely specify
an attribute in a relation.
a column in a relation.
a table in a relation.
a tuple in a relation.
A key attribute
can have NULL values.
is the extra attribute of a relation.
can have multiple data values.
can not have NULL values
Relational algebra is a procedural query language, which takes instances of relations as input and yields instances of relations as output
TRUE
FALSE
ACID properties means
Atomicity, Consistency, Isolation, and Deletion
Atomicity, Consistency, Identification, and Deletion
Atomicity, Consistency, Isolation, and Durability
Atomicity, Construction, Isolation, and Deletion
Normalization divides the larger table into the smaller table and links them using
relationship.
redundancy
hyperlink
tuples.
A relation is in 2NF, only if a relation is in 1NF and
attribute is dependent on each other.
every non-key attribute is fully dependent on primary key.
every attribute is a key attribute
primary key dependent on the other attribute.
A functional dependency is a relationship between or among
A. Entities
B. Rows
C. Attributes
D. Tables
If one attribute is determinant of second, which in turn is determinant of third, then the relation cannot be:
A. Well-structured
B. 1NF
C. 2NF
D. 3NF
Consider the schema R(S,T,U,V) and the dependencies S→T, T→U, U→V, V→S. Let R= {R1,R2} such that R1∩R2=Φ. Then the decomposition is :
A. not in 2NF
B. in 2NF but not in 3NF
C. in 3NF but not in 2NF
D. in both 2NF and 3NF
Functional Dependencies are the types of constraints that are based on______
a) Key
b) Key revisited
c) Superset key
d) None of the mentioned
Empdt1(empcode, name, street, city, state, pincode).
For any pincode, there is only one city and state. Also, for given street, city and state, there is just one pincode. In normalization terms, empdt1 is a relation in
a) 1 NF only
b) 2 NF and hence also in 1 NF
c) 3NF and hence also in 2NF and 1NF
d) BCNF and hence also in 3NF, 2NF and 1NF
There are two functional dependencies with the same set of attributes on the left side of the arrow:
A->BC
A->B
This can be combined as
a) A->BC
b) A->B
c) B->C
d) None of the mentioned
Suppose relation R(A,B,C,D,E) has the following functional dependencies:
A -> B
B -> C
BC -> A
A -> D
E -> A
D -> E
Which of the following is not a key?
a) A
b) E
c) B, C
d) D
Consider a relation R(A,B,C,D,E) with the following functional dependencies:
ABC -> DE and
D -> AB
The number of superkeys of R is:
2
7
10
12
Suppose relation R(A,B,C,D,E) has the following functional dependencies:
A -> B
B -> C
BC -> A
A -> D
E -> A
D -> E
Which of the following is not a key?
a) A
b) E
c) B, C
d) D
Normalisation is:
Removing all necessary data from a database
Organising a database to remove repeated entries and increase the accuracy of the data
Putting fields from different tables into one big database
Which of the following statements fully describes data in 2NF:
When any repeating fields have been removed and the table is given a primary key
When all repeating entries of data are removed and the fields in each table are directly related to the primary key and no fields are present that are not related to each other
When all the fields in each table are directly related to the primary key
An advantage of normalisation is:
The storage space needed for a normalised database is likely to be smaller
The process of normalising a database is very easy and doesn’t require any skill
It is possible to see previous details that have been changed, such as a customer’s address, as we can look back at an older entry
What is an atomic field?
A field that contains multiple items of data
A field that is repeated
A field that contains only one item of data
A disadvantage of normalisation is:
The data loses its integrity as some of it is removed in the normalisation process
The process of searching the database may be slower due to a higher demand on the central processing unit (CPU)
Removing redundant data means that links cannot be created between tables
A relation is in 1NF if it doesn't contain any ____________?
Determinants
Repeating groups
Null values in primary key fields
Functional dependencies
When you normalize a relation by breaking it into two smaller relations, what must you do to maintain data integrity?
Remove any functional dependencies from both relations
Assign both relations the same primary key field(s)
Create a primary key(s) for the new relation
When designing a database you should ____.
make sure entities are in normal form before table structures are created
create table structures then normalize the database
only normalize the database when performance problems occur
consider more important issues such as performance before normalizing
When designing a database you should ____.
make sure entities are in normal form before table structures are created
create table structures then normalize the database
only normalize the database when performance problems occur
consider more important issues such as performance before normalizing
When designing a database you should ____.
make sure entities are in normal form before table structures are created
create table structures then normalize the database
only normalize the database when performance problems occur
consider more important issues such as performance before normalizing
