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Consider the following relational schema pertaining to a students database.

Student: (rollno. name, address)

Enroll: (rollno. courseno. coursename) Where the primary keys are shown underlined. The number of tuples in the Student and the Enroll tables are 120 and 8 respectively. What are the maximum and the minimum number of tuples that can be present in (Student * Enroll), where * denotes natural join?

  • a)
    8, 8

  • b)
    120,8

  • c)
    960,120 

  • d)
    960,8

Correct answer is option 'D'. Can you explain this answer?
Verified Answer
Consider the following relational schema pertaining to a students data...
Student: (rollno, name, address)



  • Primary Key: rollno

  • Number of tuples: 120



Enroll: (rollno, courseno, coursename)



  • Primary Key: (rollno, courseno)

  • Number of tuples: 8



Natural Join


A natural join between the Student and Enroll tables will combine rows from both tables based on the common attribute rollno.


Minimum Number of Tuples


The minimum number of tuples in the natural join occurs when there are no matching rollno values between the two tables. However, in practice, we need at least one match for the join to yield results.


If no rollno from Enroll matches any rollno in Student, the join will produce zero tuples.


If there are matches, the minimum number of tuples is determined by the table with fewer tuples, which is Enroll in this case. Each Enroll entry needs at least one matching Student entry to form a tuple in the join.


So, the practical minimum number of tuples is 0 if no matches, otherwise at least 1, but technically, based on the fewest tuples in Enroll, the minimum could still be up to 8.


Maximum Number of Tuples


The maximum number of tuples occurs when each Enroll tuple can match multiple Student tuples, but since rollno in Student is unique, each rollno in Enroll can match only one Student tuple.


However, since we consider every tuple in Enroll can potentially join with a unique rollno in Student, and given each student (120) can enroll in multiple courses, the maximum number of tuples in the join is a product of all students and enrollments, provided the rollno in Enroll matches those in Student.


Calculations



  • Minimum: 0 (if no rollno matches between Enroll and Student), but practically considering matching scenarios, up to 8.

  • Maximum: If each of the 120 students is enrolled in multiple courses and each match is counted, the theoretical max is the product of the total rows in both tables (120 students * 8 enrollments each = 960), assuming all rollno in Enroll are present in Student.



Thus, the maximum number of tuples that can be present in the natural join is 960, and the practical minimum, considering enrollment existence, is up to 8.


Thus, the correct answer is: 960, 8
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Most Upvoted Answer
Consider the following relational schema pertaining to a students data...
Maximum and Minimum Number of Tuples in (Student * Enroll)

Given relational schema:

Student: (rollno, name, address)
Enroll: (rollno, courseno, coursename)

Where the primary keys are shown underlined. The number of tuples in the Student and the Enroll tables are 120 and 8 respectively.

Natural Join:

The natural join is a type of join operation that combines two tables based on the matching columns between them. It returns the rows from both tables where the values of the matching columns are equal.

Maximum Number of Tuples:

The maximum number of tuples in (Student * Enroll) can be calculated by multiplying the number of tuples in the Student and the Enroll tables since there is a common column (rollno) between the two tables.

Maximum number of tuples = number of tuples in Student table * number of tuples in Enroll table
= 120 * 8
= 960

Therefore, the maximum number of tuples that can be present in (Student * Enroll) is 960.

Minimum Number of Tuples:

The minimum number of tuples in (Student * Enroll) can be calculated by taking the number of tuples in the Enroll table since it is possible that some students may not have enrolled in any courses.

Minimum number of tuples = number of tuples in Enroll table
= 8

Therefore, the minimum number of tuples that can be present in (Student * Enroll) is 8.

Final Answer:

Hence, the maximum and minimum number of tuples that can be present in (Student * Enroll) are 960 and 8 respectively.
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Consider the following relational schema pertaining to a students database.Student: (rollno. name, address)Enroll: (rollno. courseno. coursename) Where the primary keys are shown underlined. The number of tuples in the Student and the Enroll tables are 120 and 8 respectively. What are the maximum and the minimum number of tuples that can be present in (Student * Enroll), where * denotes natural join?a)8, 8b)120,8c)960,120d)960,8Correct answer is option 'D'. Can you explain this answer?
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Consider the following relational schema pertaining to a students database.Student: (rollno. name, address)Enroll: (rollno. courseno. coursename) Where the primary keys are shown underlined. The number of tuples in the Student and the Enroll tables are 120 and 8 respectively. What are the maximum and the minimum number of tuples that can be present in (Student * Enroll), where * denotes natural join?a)8, 8b)120,8c)960,120d)960,8Correct answer is option 'D'. Can you explain this answer? for Computer Science Engineering (CSE) 2024 is part of Computer Science Engineering (CSE) preparation. The Question and answers have been prepared according to the Computer Science Engineering (CSE) exam syllabus. Information about Consider the following relational schema pertaining to a students database.Student: (rollno. name, address)Enroll: (rollno. courseno. coursename) Where the primary keys are shown underlined. The number of tuples in the Student and the Enroll tables are 120 and 8 respectively. What are the maximum and the minimum number of tuples that can be present in (Student * Enroll), where * denotes natural join?a)8, 8b)120,8c)960,120d)960,8Correct answer is option 'D'. Can you explain this answer? covers all topics & solutions for Computer Science Engineering (CSE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Consider the following relational schema pertaining to a students database.Student: (rollno. name, address)Enroll: (rollno. courseno. coursename) Where the primary keys are shown underlined. The number of tuples in the Student and the Enroll tables are 120 and 8 respectively. What are the maximum and the minimum number of tuples that can be present in (Student * Enroll), where * denotes natural join?a)8, 8b)120,8c)960,120d)960,8Correct answer is option 'D'. Can you explain this answer?.
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