title: Why this error: Illegal mix of collations (utf8_general_ci,IMPLICIT) and (utf8_bin,NONE) for operation '=', ON THIS QUERY?
body: <p>Query:</p>
  
  <pre><code>select *,
         (@page_path = concat(
             @page_path,
             chk_v_application_tree.alias
         )) as path
  from chk_v_application_tree 
  </code></pre>
  
  <blockquote>
    <p>[Err] 1267 - Illegal mix of collations (utf8_general_ci,IMPLICIT) and (utf8_bin,NONE) for operation '='</p>
  </blockquote>