1 SELECT 2 EXTRACT (DAY FROM DT2-DT1)*24+EXTRACT(HOUR FROM DT2-DT1) ||‘:‘||EXTRACT(MINUTE FROM DT2-DT1) ||‘:‘||EXTRACT (SECOND FROM DT2-DT1 )3 FROM(4 SELECT 5 TO_TIMESTAMP(‘2014/12/03 00:00:00‘,‘YYYY-MM-DD HH24:MI:SS‘) DT1,6 TO_TIMESTAMP(‘2014/12/04 23:59:59‘,‘YYYY-MM-DD HH24:MI:SS‘) DT27 FROM DUAL)

注：TO_TIMESTAMP日期为TO_char型两个日期直接相减得出的是天数。select sysdate-(sysdate-1) from dual;