code: def ReadClientLastPings(self,
                            min_last_ping=None,
                            max_last_ping=None,
                            fleetspeak_enabled=None,
                            cursor=None):
      
      query = "SELECT client_id, UNIX_TIMESTAMP(last_ping) FROM clients "
      query_values = []
      where_filters = []
      if min_last_ping is not None:
        where_filters.append("last_ping >= FROM_UNIXTIME(%s) ")
        query_values.append(mysql_utils.RDFDatetimeToTimestamp(min_last_ping))
      if max_last_ping is not None:
        where_filters.append(
            "(last_ping IS NULL OR last_ping <= FROM_UNIXTIME(%s))")
        query_values.append(mysql_utils.RDFDatetimeToTimestamp(max_last_ping))
      if fleetspeak_enabled is not None:
        if fleetspeak_enabled:
          where_filters.append("fleetspeak_enabled IS TRUE")
        else:
          where_filters.append(
              "(fleetspeak_enabled IS NULL OR fleetspeak_enabled IS FALSE)")
  
      if where_filters:
        query += "WHERE " + "AND ".join(where_filters)
      cursor.execute(query, query_values)
      last_pings = {}
      for int_client_id, last_ping in cursor.fetchall():
        client_id = db_utils.IntToClientID(int_client_id)
        last_pings[client_id] = mysql_utils.TimestampToRDFDatetime(last_ping)
      return last_pings
docs: Reads client ids for all clients in the database.