select TO_CHAR(TRUNC(SYSDATE)+(to_date( '31-MAY-2012 12:25', 'DD-MON-YYYY HH24:MI') 
                             - to_date( '31-MAY-2012 10:37', 'DD-MON-YYYY HH24:MI')), 
        'HH24:MI:SS') from dual

——结果:01:48:00

好吧，这不是OP要求的，但这是我想做的:-)

select 
unix_timestamp('2007-12-30 00:00:00') - 
unix_timestamp('2007-11-30 00:00:00');

SELECT TIMESTAMPDIFF(HOUR,NOW(),'2013-05-15 10:23:23')
   calculates difference in hour.(for days--> you have to define day replacing hour
SELECT DATEDIFF('2012-2-2','2012-2-1')

SELECT TO_DAYS ('2012-2-2')-TO_DAYS('2012-2-1')

SELECT TIMEDIFF('2007-12-31 10:02:00','2007-12-30 12:01:01');
-- result: 22:00:59, the difference in HH:MM:SS format


SELECT TIMESTAMPDIFF(SECOND,'2007-12-30 12:01:01','2007-12-31 10:02:00'); 
-- result: 79259  the difference in seconds

因此，您可以使用TIMESTAMPDIFF来实现您的目的。

为什么不干脆

从表中选择Sum(Date1 - Date2)

Date1和date2是datetime

select TO_CHAR(TRUNC(SYSDATE)+(to_date( '31-MAY-2012 12:25', 'DD-MON-YYYY HH24:MI') 
                             - to_date( '31-MAY-2012 10:37', 'DD-MON-YYYY HH24:MI')), 
        'HH24:MI:SS') from dual

——结果:01:48:00

好吧，这不是OP要求的，但这是我想做的:-)