title: Dataframe.isin() giving this error: The truth value of a DataFrame is ambiguous
body: <p>Can you help with this error: what am I doing wrong with the df.isin function?</p>
  
  <pre><code>cursor = con.cursor()
  cursor.execute("""SELECT distinct date FROM raw_finmis_online_activation_temp""")
  existing_dates = [x[0] for x in cursor.fetchall()]
  
  if df[df['date'].isin(existing_dates)]:
      print "Yes it's in there"
  else:
      print "N"
  </code></pre>
  
  <p>It's giving me this error:</p>
  
  <blockquote>
    <p>ValueError: The truth value of a DataFrame is ambiguous. Use a.empty,
    a.bool(), a.item(), a.any() or a.all().</p>
  </blockquote>