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1. Which of the following is not a relational algebra function?
a) Select
b) Project
c) Manipulate
d) Union

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Answer: c [Reason:] 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.

2. The select operation’s function in relational algebra is identical to the _______ clause in SQL
a) where
b) from
c) select
d) none of the mentioned

View Answer

Answer: a [Reason:] 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.

3. The project operation’s function in relational algebra is identical to the _______ clause in SQL
a) where
b) from
c) select
d) none of the mentioned

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Answer: c [Reason:] 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.

4. What does the following relational operation perform?
ρx(A1,A2,A3…) (E)
a) It returns the result of expression E with the previous attribute names
b) It returns the result of expression E renaming the attributes as A1, A2, …
c) It returns the result of the relation E but saves the old attributes
d) None of the mentioned

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Answer: b [Reason:] 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.

5. What does the following relational algebra expression do?
σamount > 1200 (loan)
a) Finds all the tuples in loan
b) Finds the tuples in loan where the amount is greater than 12000
c) Finds all the tuples in loan where the amount is greater than 1200
d) Finds all the amounts in loan where the number of values is greater than 1200

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Answer: c [Reason:] 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.

6. How is the left outer join symbol represented in relational algebra?
a) ⟕
b) ⟖
c) ⟗
d) ⋈

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Answer: a [Reason:] 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.

7. How is the right outer join symbol represented in relational algebra?
a) ⟕
b) ⟖
c) ⟗
d) ⋈

View Answer

Answer: b [Reason:] 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.

8. Πcustomer_name, loan_number, amount (borrower ⋈loan)
What does the above expression perform?
a) It finds the customer_name, loan_number and amount from borrower
b) It finds the customer_name, loan_number and amount from loan
c) It finds the customer_name, loan_number and amount from the full outer join of borrower and loan
d) It finds the customer_name, loan_number and amount from the natural join of borrower and loan

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Answer: d [Reason:] 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.

9. Updating, Deleting and Inserting in relational algebra is done using the ________ operator
a) Assignment
b) Modification
c) Alteration
d) Inclusion

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Answer: a [Reason:] Updating, Deleting and Inserting in relational algebra is done using the assignment operator.

10. State true or false: There exists a division operator in Relational Algebra
a) True
b) False

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Answer: a [Reason:] 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.

11. The collections on which aggregate functions can operate are called as __________
a) Multisets
b) Multivalues
c) Multicollections
d) Multivariables

View Answer

Answer: a [Reason:] The collections on which aggregate functions can operate are called as multisets. Sets are a special case of multisets.