title: Primary key detection
body: <p>I have imported the data into an database.</p>
  
  <p>Patient(pt_id,pt_name,pt_type,pt_loc)</p>
  
  <p>Now , I want to find which of these a primary (have unique) values.</p>
  
  <p>Any way I could found is </p>
  
  <pre><code>     select count(pt_id) from patient
       select count(distinct pt_id) from patient
  </code></pre>
  
  <p>would return the same value</p>
  
  <p>Any input would be great :)</p>
  
  <p>Thanks!!!</p>