GATE CS 2022 Set 1 — Question 56

NAT+2 / -0MediumDivisionRelational ModelDatabasesSubqueriesSQL

Databases → Relational Model → Division

Last updated 5 September 2026

Question

Consider the relational database with the following four schemas and their respective instances. Student (sNo, sName, dNo) Dept (dNo, dName) Course (cNo, cName, dNo) Register (sNo, cNo) Student sNo sName dNo S01 James D01 S02 Rocky D01 S03 Jackson D02 S04 Jane D01 S05 Milli D02 Dept dNo dName D01 CSE D02 EEE Course cNo cName dNo C11 DS D01 C12 OS D01 C21 DE D02 C22 PT D02 C23 CV D03 Register sNo cNo S01 C11 S01 C12 S02 C11 S03 C21 S03 C22 S03 C23 S04 C11 S04 C12 S05 C11 S05 C21 SQL Query: SELECT * FROM Student AS S WHERE NOT EXIST (SELECT cNo FROM Course WHERE dNo = "D01" EXCEPT SELECT cNo FROM Register WHERE sNo = S.sNo) The number of rows returned by the above SQL query is___________.

Correct answer 2 to 2 Solution The SQL query performs a relational division operation. It selects all students from the Student table who have registered for every course offered by department 'D01'. 1. Identify courses in department 'D01': From the Course table, these are {C11, C12}. 2. Check each student's registrations from the Register table: S01: Registered for {C11, C12}. (Matches all D01 courses) S02: Registered for {C11}. (Missing C12) S03: Registered for {C21, C22, C23}. (Missing C11, C12) S04: Registered for {C11, C12}. (Matches all D01 courses) S05: Registered for {C11, C21}. (Missing C12) The students who satisfy the condition are S01 and S04. Thus, 2 rows are returned. Turn this into a strength. Explore AI-powered practice and doubt support with Success Tracker.

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Correct answer 2 to 2 Solution The SQL query performs a relational division operation. It selects all students from the Student table who have registered for every course offered by department 'D01'. 1. Identify courses in department 'D01': From the Course table, these are {C11, C12}. 2. Check each student's registrations from the Register table: S01: Registered for {C11, C12}. (Matches all D01 courses) S02: Registered for {C11}. (Missing C12) S03: Registered for {C21, C22, C23}. (Missing C11, C12) S04: Registered for {C11, C12}. (Matches all D01 courses) S05: Registered for {C11, C21}. (Missing C12) The students who satisfy the condition are S01 and S04. Thus, 2 rows are returned.

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