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
How many distinct tuples are there in a relation instance with cardinality 22 ?
22
11
1
none
Related fields in a database are grouped to form a
data file
data record
menu
bank
In the relational model, cardinality is the
number of tuples
number of attributes
number of tables
number of constraints
A set of possible data values is called
attribute
degree
tuple
domain
Abstraction of the database can be viewed as
two levels
four levels
three levels
one level
Which of the following operations is used if we are interested only in certain columns of a table ?
PROJECTION
SELECTION
UNION
SELECT
The person who interact the database through query language is called
DBA
Application programmers
Sophisticated users
Naive user
Key to represent relationship between tables is called
primary key
candidate key
foreign key
alternate key
