with t as
(select to_timestamp(\'2015-01-01 11:13:15.023456\',
\'yyyy-mm-dd hh24:mi:ss.ff9\') t1,
to_timestamp(\'2015-01-01 12:13:15.123556\',
\'yyyy-mm-dd hh24:mi:ss.ff9\') t2
from dual)
select abs((trunc(t1 - 0, \'mi\') - trunc((t2 - 0), \'mi\')) * 24 * 60 * 60 +
extract(second from t1 - t2))
from t
输出结果： 3600.1001