title: SQL : Check if primary key is foreign key
body: <p>I want to extract the <strong>name of</strong> primary key column of table if it is also foreign key from information schema 
  like two tables :</p>
  
  <pre><code>Student 
  std_id  std_name
  </code></pre>
  
  <p>And</p>
  
  <pre><code>PHDstudent
  std_id   reaserchfield
  </code></pre>
  
  <p>That std_id in PHDstudent is primary key and foreign key at same time that refers to Student table. </p>