The minimal set of super key is called
Primary key
Secondary key
Candidate key
Foreign key
Correct Answer :
C. Candidate key
Related Questions
A transaction has following states
i) Active
ii) Fail
iii) Abort
iv) Commit
i and ii only
ii and iii only
i and iii only
iii and iv only
Authorization command in SQL
Allow
Access
Grant
none of the above
Object based data models are used in describing the abstraction of the following levels?
Conceptual and view
Only physical
Physical and conceptual
Only conceptual
Which topology requires a central controller or hub?
Ring
Tree
Switch
Graph
In two-phase locking protocol the two phases are
growing phase and shrinking phase
execution phase and blocking phase.
running phase and sleeping phase.
none of the above
Extended Entity Relationship model consists of which of the following
i) Specialization
ii) Generalization
iii) Categorization
i and ii only
ii and iii only
i and iii only
All i, ii iii
Which one of the following is provided by a data dictionary ?
User data
Database structure data
Sorted data
Functional data
The ability to modify the conceptual schema without causing any change to the application program is known as
Physical data independence
Logical data independence
External data independence
Static data
As a side-effect of database update ,the system automatically executes a statement called
a view
a grant permission
a trigger
all of the above
Which of the following file organization provides very fast access to any arbitrary record of a file?
Ordered file
Unordered file
Hashed file
B-tree
EEPROM
Electrically Extractable Programmable Read Only Memory
Electrically Erasable Programmable Read Only Memory
Electronically Erasable Programmable Read Only Memory
Electrically Erasable Programmable Read Only Memory
A logical schema
is the entire database.
is a standard way of organizing information into accessible parts.
describes how data is actually stored on disk.
both A) and C)
Secondary storage
magnetic disk
magnetic tape
juke box
cache
Event condition action model is related to
Views
Cursors
Triggers
None of these.
Relational Algebra is
Data Definition Language.
Data Manipulation Language
Procedural query Language
None of the above
What is ACID properties of Transactions?
Atomicity, Consistency, Isolation, Database
Atomicity, Consistency, Isolation, Durability
Atomicity, Consistency, Inconsistent, Durability
Automatically, Concurrency, Isolation, Durability
Attenuation can be also expressed in decibel dB) and commonly used because.
i) Signal strengths often fall off logarithmically
ii) Cascade losses and gains can be calculated with simple additions and subtractions
i only
ii only
Both A and B
None of the above
The degree of the table with 500 rows and 7 columns is
500
7
3500
none of these
Radio frequencies below ............. are more suitable for omnidirectional applications.
300MHz
1GHz
5GHz
10 GHz
Referential integrity
controls relationships between operations of an object
controls relationships between instances of a class
controls relationships between attributes in a table
controls relationships between tables in a database
A relation is said to be in ………. If it doesnt contain partial dependency
1NF
2NF
3NF
BCNF
.................. occurs due to velocity of propagation the frequency varies. Thus various frequency components of a signal arrive at the receiver at different times.
Noise
Delay distortion
Attenuation distortion
Dispersion
In this data model each record can hae more than one parent
Hierarchical model
E-R model
Network based model
none of these
What is the result of the following SQL statement ?
SELECT A.emp_Name, B.ph_num
FROM emp A LEFT OUTER JOIN phone B
ON A. emp_ID = B.emp_ID
A list of employees phone number
A list of all employees that have spouses, with phone number included in the list
A list of all employees names, including the phone number if they have one
Two lists : One list of employees, the other of phone numbers
The mode in which data item may be locked
Partner
Mutual
Exclusive
Atomic
Which of the following is/are error-free channel(s)
i) Noisy channel
ii) Noiseless channel
i only
ii only
Both
None of these
The left outer join takes all tuples
in the left relation which didnt match with any tuple in right relation
in the left relation which matched with a tuple in right relation
in the right relation which didnt match with any tuple in left relation
in the right relation which matched with a tuple in left relation
Which of the following is also known as Offline storage ?
primary storage
secondary storage
tertiary storage
none of the above
Disk storage is referred to as
sequential access storage
direct access storage
random access storage
none of the above
Select the incorrect statement(s)
i) Foreign key values can be left blank
ii) In SQL duplicates may be present
iii) Theta join operation doesnt remove duplicate columns.
iv) NULL value means string of blank characters.
i ,iii only
ii, iv only
iii, iv only
ii, iii, iv