Database Interaction Question

Hi guys, I’m fairly new to WP plugin coding and want to find the best way to accomplish this. I need to pull a list of comments containing a specifically formatted link and then cycle through them to create a XML file. Is there a built in function that would allow this and if not what is the WP approved version of this:

$result = mysql_query( "SELECT * FROM $wpdb->comments WHERE comment_content LIKE '%<a href=%nofollow%' );
if ($result && mysql_num_rows($result) > 0) {
  while ($row = mysql_fetch_array($result)) {
    // do it you will
  }
  mysql_free_result();
}

I’ve been looking through the docs but haven’t found exactly what I needed. Any help you can offer would be great.