title: maximum and minimum number of tuples in natural join
body: <p>I came across a question that states</p>
  
  <p>Consider the following relation schema pertaining to a students </p>
  
  <ul>
  <li>database: Student (<strong>rollno</strong>, name, address) </li>
  <li>Enroll (<strong>rollno, courseno</strong>, coursename) </li>
  </ul>
  
  <p>where the primary keys are shown underlined. The number of tuples in the 
      Student and Enroll tables are 120 and 8 respectively. What are the maximum 
      and minimum number of tuples that can be present in (Student * Enroll), 
      where '*' denotes natural join ?</p>
  
  <p>I have seen several solutions on Internet like <a href="http://learn.hackerearth.com/question/79/maximum-and-minimum-number-of-tuples-in-a-natural-join/" rel="nofollow">this</a>  or <a href="http://www.sitams.org/cource/gate/it/DBMS_IT_GATE.pdf" rel="nofollow">this</a> </p>
  
  <p>As per my understanding. maximum tuples should be 8 and minimum should be 8 as well, since for each (rollnum,course) there should be a roll num in Students. Anyone who can help in this regard</p>