title: 1062 Error (duplicate entry) with `ALTER IGNORE TABLE ADD PRIMARY KEY` query
body: <p>As I know from DOCs and from <a href="https://stackoverflow.com/questions/3311903/remove-duplicate-rows-in-mysql">other questions</a> such a query should silently drop rows with duplicated <code>id</code>. However MySQL throws an error:</p>
  
  <p><a href="https://i.stack.imgur.com/WCk3n.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/WCk3n.png" alt="enter image description here"></a></p>
  
  <p>This is phpmyadmin output.</p>
  
  <p>Why MySQL did not dropped rows with duplicated id? Any ideas?</p>