Which of the following operations need the participating relations to be union compatible ?
UNION
INTERSECTION
SET DIFFERENCE
All of the above
An advantages 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
Cartesian product in relational algebra is
a unary operator
a binary operator
a ternary operator
not defined
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 the relational model, cardinality is the
number of tuples
number of attributes
number of tables
number of constraints
Abstraction of the database can be viewed as
two levels
four levels
three levels
one level
In the abstraction of a database system the external level is the
physical level
logical level
conceptual level
view level
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
How many distinct tuples are there in a relation instance with cardinality 22 ?
22
11
1
none
Which of the following operations is used if we are interested only in certain columns of a table ?
PROJECTION
SELECTION
SELECT
