title: 1452 - Cannot add or update a child row: a foreign key constraint fails
body: <p>I'm getting this error: </p>
  
  <blockquote>
    <p>1452 - Cannot add or update a child row: a foreign key constraint
    fails.</p>
  </blockquote>
  
  <p>I've located them and try to get rid of the references with</p>
  
  <pre><code>alter table tillhör drop foreign key kat_id;
  </code></pre>
  
  <p>But getting this error instead:</p>
  
  <blockquote>
    <p>#1025 - Error on rename of '.\recept\tillh@1ir' to
    '.\recept#sql2-1570-3cb' (errno: 152).</p>
  </blockquote>
  
  <p>What do I do wrong?</p>