A file manipulation command that extracts some of the records from a file is called
SELECT
PROJECT
JOIN
PRODUCT
In a table Employee Emp- code, Pan_ no are the candidate keys. If Emp_ code is taken as the primary key then Pan_ no is _________ key.
candidate key
alternate key
primary key
foreign key
A set of possible data values is called
attribute
degree
tuple
domain
Cartesian product in relational algebra is
a unary operator
a binary operator
a ternary operator
not defined
In the relational model, cardinality is the
number of tuples
number of attributes
number of tables
number of constraints
Key to represent relationship between tables is called
Who is responsible for managing and controlling the activities associated with the database ?
Database administrator
Programmer
Naive user
End user
The result of the UNION operation between R1 and R2 is a relation that includes
all the tuples of R1
all the tuples of R2
all the tuples of R1 and R2
all the tuples of R1 and R2 which have common columns
Abstraction of the database can be viewed as
two levels
four levels
three levels
one level
An instance of relational schema R (A,B,C) has distinct values of A including NULL values. Which one of the following is true?
A is a candidate key
A is not a candidate key
A is a primary key
Both a and c
