title: Cardinality and Relationship among tables
body: <p>There is a table named <code>Department</code>, which shows the various departments of a University.<br>
  And there is a table named <code>Branch</code>, which shows various branches (such as electrical, computer science, mechanical, automobile, law, literature etc.)</p>
  
  <p>Conditions:</p>
  
  <ol>
  <li>A <code>Department</code> can have any number of <code>Branch</code>es.</li>
  <li>A <code>Branch</code> can be associated to single <code>Department</code>.</li>
  </ol>
  
  <p>It means the cardinality between <code>Department</code> : <code>Branch</code> is "one to many".</p>
  
  <p>Now the problem is, in this kind of situation, if I make <code>dept_id</code> (an attribute of table: <code>Department</code>) as primary key. How would I be able to associate more than one <code>branch_id</code> ( an attribute of table : <code>Branch</code>), because if I do it so, I may violate the primary key condition of <code>dept_id</code> itself.</p>
  
  <p>How to deal with cardinality and making foreign key both go hand in hand?</p>