1
GATE CSE 2004
MCQ (Single Correct Answer)
+2
-0.6
Consider two tables in a relational database with columns and rows as follows:

 Table: Student

Roll_no Name Dept_id
1 ABC 1
2 DEF 1
3 GHI 2
4 JKL 3

 Table: Department

Dept_id Dept_name
1 A
2 B
3 C

Roll_no is the primary key of the Student table, Dept_id is the primary key of the Department table and Studetn.Dept_id is a foreign key from
Department. Dept_id.

What will happen if we try to execute the following two SQL statements?
(i) update Student set Dept_id = Null where Roll_no =1
(ii) update Department set Dept_id = Null where Dept_id =1
A
Both (i) and (ii) will fail
B
(i) will fail but (ii) will succeed
C
(i) will succeed but (ii) will fail
D
Both (i) and (ii) will succeed
2
GATE CSE 2004
MCQ (Single Correct Answer)
+1
-0.3
Let R1 (A, B, C) and R2 (D, E) be two relation schema, where the primary keys are shown underlined, and let C be a foreign key in R1 referring to R2. Suppose there is no violation of the above referential integrity constraint in the corresponding relation instances r1 and r2. Which one of the following relational algebra expressions would necessarily produce an empty relation?
A
$$\prod\nolimits_D {\left( {{r_2}} \right)} - \prod\nolimits_C {\left( {{r_1}} \right)} $$
B
$$\prod\nolimits_C {\left( {{r_1}} \right)} - \prod\nolimits_D {\left( {{r_2}} \right)} $$
C
$$\prod\nolimits_D {\left( {{r_1}{ \Join _{C \ne D}}{r_2}} \right)} $$
D
$$\prod\nolimits_C {\left( {{r_1}{ \Join _{C = D}}{r_2}} \right)} $$
3
GATE CSE 2004
MCQ (Single Correct Answer)
+2
-0.6
Consider the relation Student (name, sex, marks), where the primary key is shown underlined, pertaining to students in a class that has at least one boy and one girl. What does the following relational algebra expression produce? (Note: ρ is the rename operator). GATE CSE 2004 Database Management System - Relational Algebra Question 19 English
A
names of girl students with the highest marks
B
names of girl students with more marks than some boy student
C
names of girl students with marks not less than some boy student
D
names of girl students with more marks than all the boy students
4
GATE CSE 2004
MCQ (Single Correct Answer)
+1
-0.3
Which level of locking provides the highest degree of concurrency in a relational database?
A
Page.
B
Table.
C
Row.
D
Page, table and row level locking allow the same degree of concurrency.
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