code: def is_subdomain_zonefile_hash(self, fqn, zonefile_hash, cur=None):
          
          sql = 'SELECT COUNT(zonefile_hash) FROM {} WHERE fully_qualified_subdomain = ? and zonefile_hash = ?;'.format(self.subdomain_table)
          args = (fqn,zonefile_hash)
  
          cursor = None
          if cur is None:
              cursor = self.conn.cursor()
          else:
              cursor = cur
  
          rows = db_query_execute(cursor, sql, args)
          
          count = None
          for row in rows:
              count = row['COUNT(zonefile_hash)']
              break
  
          return (count > 0)
docs: Does this zone file hash belong to this subdomain?