为什么在distance和air_time列中使用sum时,此代码显示无效标识符?当未使用sum时,此语句处理成功,但使用sum I get error?对于此语句,我需要使用sum。USING (SELECT DISTINCT TIME_ID, FLIGHT_KEY, AEROPLANE_KEY, SUM(DISTANCE) AS TOTAL_DISTANCE, SUM(AIR_TIMEON (F.FK1_TIME_ID = S.TIME_ID
AND F.FK2_FLIGHT_KEY = <e