title: key constraint fails - what does it mean?
body: <p>I am getting this error, when saving data to my db:</p>
  
  <blockquote>
    <p>SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: 
    a foreign key constraint fails (<code>mydb</code>.<code>samplelist_item</code>, CONSTRAINT <code>FK_SAMPLELIST_ITEM_SAMPLELIST</code> 
    FOREIGN KEY (<code>samplelist_id</code>) REFERENCES <code>samplelist</code> (<code>samplelist_id</code>) ON DELETE CASCADE ON UPDATE CASCADE)</p>
  </blockquote>
  
  <p>Not sure what the problem is.</p>