fantuan

如下是建立流计算的语句，trigger 设置的是 at_once ``` create stream if not exists device_online_stats fill_history 1 trigger at_once into sensor_center_dev_v2.st_stream_device_online_stats subtable(concat('t_stream_device_oline_stats_', tbname)) as select last(device_model) device_model, last(device_str_id) device_str_id, bool_v, _wstart `start`, _wend `end`, timediff(_wstart,_wend,1m)...