The Relational Algebra

Question 1
Marks : +2 | -2
Pass Ratio : 100%
The select operation’s function in relational algebra is identical to the _______ clause in SQL
where
from
select
none of the mentioned
Explanation:
The select operation’s function in relational algebra is identical to the where clause in SQL standard. It is therefore used to check for a particular condition.
Question 2
Marks : +2 | -2
Pass Ratio : 100%
State true or false: There exists a division operator in Relational Algebra
True
False
Explanation:
The division is a binary operation that is labeled as R ÷ S. The result consists of the restrictions of tuples in R to the attributes unique to R, i.e., in the relation R but not in the relation S.
Question 3
Marks : +2 | -2
Pass Ratio : 100%
Updating, Deleting and Inserting in relational algebra is done using the ________ operator
Assignment
Modification
Alteration
Inclusion
Explanation:
Updating, Deleting and Inserting in relational algebra is done using the assignment operator.
Question 4
Marks : +2 | -2
Pass Ratio : 100%
What does the following relational operation perform?
It returns the result of expression E with the previous attribute names
It returns the result of expression E renaming the attributes as A1, A2, …
It returns the result of the relation E but saves the old attributes
None of the mentioned
Explanation:
If a relational-algebra expression E has arity n, then the above expression returns the result of expression E under the name X, and with the attributes renamed to A1 , A2 , …., An.
Question 5
Marks : +2 | -2
Pass Ratio : 100%
The project operation’s function in relational algebra is identical to the _______ clause in SQL
where
from
select
none of the mentioned
Explanation:
The project operation’s function in relational algebra is identical to the select clause in SQL standard. It is used to list the attributes that are to be displayed.
Question 6
Marks : +2 | -2
Pass Ratio : 100%
Which of the following is not a relational algebra function?
Select
Project
Manipulate
Union
Explanation:
There does not exist any operation named as manipulate operation in relational algebra. The union gives the union of two sets. Project is similar to select in SQL and select is similar to where in SQL.
Question 7
Marks : +2 | -2
Pass Ratio : 100%
How is the left outer join symbol represented in relational algebra?
⟕
⟖
⟗
⋈
Explanation:
The symbol of the left outer join is similar to the symbol of the natural join but it has two dashes on the top and bottom left side.
Question 8
Marks : +2 | -2
Pass Ratio : 100%
What does the following relational algebra expression do?
Finds all the tuples in loan
Finds the tuples in loan where the amount is greater than 12000
Finds all the tuples in loan where the amount is greater than 1200
Finds all the amounts in loan where the number of values is greater than 1200
Explanation:
The above expression finds all the tuples in loan wherever the amount is greater than 1200. Because the condition specifies that the amount should be greater than 1200.
Question 9
Marks : +2 | -2
Pass Ratio : 100%
Πcustomer_name, loan_number, amount (borrower ⋈loan)
It finds the customer_name, loan_number and amount from borrower
It finds the customer_name, loan_number and amount from loan
It finds the customer_name, loan_number and amount from the full outer join of borrower and loan
It finds the customer_name, loan_number and amount from the natural join of borrower and loan
Explanation:
The above relational algebra expression finds the customer_name, loan_number and amount from the natural join of borrower and loan as the attributes are written next to the project symbol and the relation to be extracted from is mentioned in the parentheses which is the natural join of borrower and loan.
Question 10
Marks : +2 | -2
Pass Ratio : 100%
How is the right outer join symbol represented in relational algebra?
⟕
⟖
⟗
⋈
Explanation:
The symbol of the right outer join is similar to the symbol of the natural join but it has two dashes on the top and bottom right side.