date help

[ali560045]

i have a table called std_detail.I m geting the max and min date from the table and then finding the difference b/w dates:

ENAME TIME_VALUE
naveed 09/10/2008 08:30:50
amit 10/30/2008 00:00:00
raja 11/17/2008 03:30:50
fasi 10/25/2008 01:30:50
yuvi 06/27/2008 17:55:06
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select
(select to_char(max(time_value),'dd/mm/RR HH:MI:SS') from std_detail) -
(select to_char(min(time_value),'dd/mm/RR HH:MI:SS') from std_detail) "Days diff"
from dual

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the above command not working showing ORA-01722.



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if i use this sql :

select
(select to_date(max(time_value),'dd/mm/yyyy hh:mi:ss') from std_detail) -
(select to_date(min(time_value),'dd/mm/yyyy hh:mi:ss') from std_detail) "Days diff"
from DUAL


above sql gives only the date diff but not the hour min diff alongside date