title: MySQL Error: Duplicate entry 'xxx' for Primary Key
body: <p>I have table MySQL with Primary Key Composed of 2 fields, as below</p>
  
  <p><a href="https://i.stack.imgur.com/mpSkb.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/mpSkb.jpg" alt="Script showing Primary Key"></a></p>
  
  <p>Already existing records in the table are:</p>
  
  <p><a href="https://i.stack.imgur.com/Z1YIP.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Z1YIP.jpg" alt="Existing Records"></a></p>
  
  <p>The INSERT query I am issuing is: </p>
  
  <p><a href="https://i.stack.imgur.com/UlZX3.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/UlZX3.jpg" alt="The Query"></a></p>
  
  <p>When I run the query:</p>
  
  <pre><code>INSERT INTO `case_data` 
  VALUES ('WCD/2016/1000017', 2, '2016-09-29', 'WCD',***********************
  </code></pre>
  
  <p>The error message displayed is:</p>
  
  <blockquote>
    <p>[Err] 1062 - Duplicate entry 'WCD/2016/1000017' for key 'PRIMARY'</p>
  </blockquote>
  
  <p>Am I violating the Primary Key constraint?</p>
  
  <p>Thanks in advance.</p>