Oracle 计算时间差

SELECT SYSDATE - to_date(substr(TIMEKEY,1,14),'yyyy-mm-dd hh24:mi:ss') FROM Z_JOB_RUN_TIME  WHERE
JOBNAME  LIKE 'LoadSpcData_%'
AND SYSDATE - min(TIMEKEY) > 
ORDER BY TIMEKEY DESC
--JOBNAME = 'LoadSpcData_OC_P_N_RS[(R|S)]'
UPDATETIME>=to_date('2018-12-29 09:00:00','yyyy/mm/dd HH24:MI:SS')  
SELECT ROUND(to_number(sysdate - to_date(SUBSTR('20190109155459578000',1,14),'yyyy-mm-dd hh24:mi:ss'))*24*60*60) FROM dual
SELECT to_date(SUBSTR('20190109155459578000',1,14),'yyyy-mm-dd hh24:mi:ss') FROM dual
SELECT SYSDATE FROM dual
ROUND(TO_NUMBER(END_DATE - START_DATE) * 24 * 60 * 60)
2019-01-09 16:44:29
2019-01-09 15:54:59
0.0344444444444444444444444444444444444444