Abstraction of the database can be viewed as
two levels
four levels
three levels
one level
Which database level is closest to the users?
external
internal
physical
conceptual
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
Related fields in a database are grouped to form a
data file
data record
menu
bank
How many distinct tuples are there in a relation instance with cardinality 22 ?
22
11
1
none
Cartesian product in relational algebra is
a unary operator
a binary operator
a ternary operator
not defined
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
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
Which of the following operations need the participating relations to be union compatible ?
UNION
INTERSECTION
SET DIFFERENCE
All of the above
