How do I use "IGNORE" in a database query?
What you want is a MERGE query with no UPDATE part. Something like this should work:

db_merge('the_table')
  -&gt;key(array(
      'nid' =&gt; 8,
      'language' =&gt; Chinese,
  ))
  -&gt;insertFields(array(
    'nid' =&gt; 8,
    'language' =&gt; Chinese,
  ));
  -&gt;execute();