Assignment: Fundamentals of Databases
Question 1
Define and explain the following terms (give examples):
- Domain of an attribute
- Atomic
- Super key
- Candidate key
- Primary key
Question 2
Consider the following three relations:
For each of the following relational expressions, compute the result on the above relations and submit only the final answer. For example, for query: πB,D(S), the result should be entered as: {(a, x), (b, y), (b, x), (c, y)}.
a. πA,D(R×S)
b. πA,D(R∞S)
c. πE(T)-πE(S∞T)
Question 3
Consider the relational database of instructor:
|
ID
|
Name
|
DOB
|
Gender
|
Dept_No
|
|
E101
|
Ahmed
|
15-JUL-1986
|
M
|
2
|
|
E103
|
Ali
|
04-MAY-1989
|
M
|
2
|
|
E104
|
Sara
|
29-OCT-1987
|
F
|
1
|
|
E102
|
Omar
|
20-MAY-1988
|
M
|
3
|
|
E105
|
Hind
|
23-JAN-1980
|
F
|
4
|
a. Identify at least four possible superkeys?
b. Identify at least three possible candidate keys?
Relational Algebra
Purpose
The purpose of this assignment is to help you learn more about the relational algebra.
Brief Introduction
Relational Algebra
Relational algebra is a procedural query language, which takes instances of relations as input and yields instances of relations as output. It uses operators to perform queries. An operator can be either unary or binary. They accept relations as their input and yield relations as their output.
Action Items
• You are requested to submit one example of relational algebra.