title: This table does not contain a unique column. Grid edit, checkbox, Edit, Copy and Delete features are not available
body: <p>The error generated in phpMyAdmin is:</p>
  <blockquote>
  <p>This table does not contain a unique column. Grid edit, checkbox, Edit, Copy and Delete features are not available.</p>
  </blockquote>
  <p>What does this error message mean and how can I fix it?</p>