The ______ key of a relation is the attribute (column) or collection of attributes, which uniquely identify a given tuple.
Primary
Foreign
Candidate
Alternate
Correct Answer :
A. Primary
Related Questions
What is a disjoint less constraint?
It requires that an entity belongs to no more than one level entity set.
The same entity may belong to more than one level.
The database must contain an unmatched foreign key value.
An entity can be joined with another entity in the same level entity set.
Protection of data from unauthorized Disclosure results in loss of _______
Integrity
Availability
Confidentiality
Discretionary Security
Which of the following concurrency control schemes is not based on the serializability property?
Two - phase locking
Graph-based locking
Time-stamp based locking
None of these .
In multiple granularity of locks SIX lock is compatible with
IX
IS
S
SIX
A top-to-bottom relationship among the items in a database is established by a
Hierarchical schema
Network schema
Relational Schema
All of the above
Data independence means
data is defined separately and not included in programs.
programs are not dependent on the physical attributes of data
programs are not dependent on the logical attributes of data
both B and C
Use of UNIQUE while defining an attribute of a table in SQL means that the attribute values are
distinct values
cannot have NULL
both (A) & (B)
same as primary key
………………… approach reduces time and effort required for design and lesser risk in database management.
Single global database
Multiple databases
Top-down approach
None of the above
In a multi-user database, if two users wish to update the same record at the same time, they are prevented from doing so by
jamming
password
documentation
record lock
Processed data is called _____
Raw data
Source
Information
Useful data
Data items grouped together for storage purposes are called a
record
string
title
list
A data type or format is specified for each _________
Relation
Tuple
Database
Domain
Which of the following is not a property of transactions?
Atomicity
Concurrency
Isolation
Durability
In a relational schema, each tuple is divided into fields called
Relations
Queries
Domains
All of the above
A DBMS is a ____ user if at most one user can use the system and is mostly restricted to personal computer systems.
None
Multi
Single
Concurrent
The set of all values that can be taken by the attribute is called as _______ of the attribute.
Tuple
Cardinality
Degree
Domain
The division operator divides a dividend A of degree m+n by a divisor relation B of degree n and produces a result of degree
m - 1
m + 1
m * m
m
DBMS is a collection of _____ that enables user to create and maintain a database.
Keys
Program
Translators
Language Activity
A weak entity has an ______ dependency on its owner entity, which can be used for both ON UPDATE and ON DELETE.
Direct
Indirect
Existence
No
The normalization was first proposed by .
Code
Codd
Boyce Codd
Boyce
In an ER model,_____ is described in the database by storing its data.
Entity
Attribute
Relationship
Notation
The common column is eliminated in
theta join
outer join
natural join
composed join
______ keyword is used to find the number of values in a column.
TOTAL
ADD
COUNT
SUM
The clause alter table in SQL can be used to
add an attribute
delete an attribute
alter the default values of an attribute
all of the above
A transaction is in state after the final statement has been executed.
partially committed
active
committed
none of the above
A _____ is a logical unit of database processing that includes one or more data access operations that can include insertion, deletion, modification or retrieval operations.
Database
Data
Transaction
Record
Immediate database modification technique uses
Both undo and redo.
Undo but no redo.
Redo but no undo.
Neither undo nor redo.
When an E-R diagram is mapped to tables, the representation is redundant for
weak entity sets
weak relationship sets
strong entity sets
strong relationship sets
Which of the following is not a characteristic of a relational database model?
Table
Tree like structure
Complex logical relationship
Records
The normal form that is not necessarily dependency preserving is
2NF
3NF
BCNF
4NF