To calculate elapsed time between two timestamp attributes

Question

Hello,
I have two timestamp attributes (create_tmstmp & elapsed_tmstmp) in a table.
It has two rows and I need the difference in seconds between these two attributes.
The below query is returning negative value and incorrect value.
Any help is appreciated.
Row 1:
Create_tmstmp : 2/2/2010 9:53:15.832 PM
Elapsed_tmstmp : 2/3/2010 9:49:47.527 AM
Row 2:
Create_tmstmp : 2/3/2010 5:35:47.614 AM
Elapsed_tmstmp : 2/3/2010 11:03:15.937 AM
Select
( (extract(day from elapsed_tmstmp )-extract(day from create_tmstmp))*86400+
(extract(hour from elapsed_tmstmp )-extract(hour from create_tmstmp))*3600+
(extract(minute from elapsed_tmstmp)-extract(minute from create_tmstmp))*60+
(extract(second from elapsed_tmstmp)-extract(second from create_tmstmp))*1000) completed_tmstmp
From table_a;
The output is :
completedtmstmp_
74655
-11997
Thanks.
Edited by: solsam on Feb 4, 2010 11:57 AM

Answer 1

hi,
The problem with cast to date is
SQL> select to_char(cast(to_timestamp('2/2/2010 9:53:15.832 PM','mm/dd/yyyy hh:mi:ss.ff pm') as dat
e),'mm/dd/yyyy hh:mi:ss pm') from dual
2 ;
TO_CHAR(CAST(TO_TIMEST
02/02/2010 09:53:16 pm
so cast rounds it up, resulting in:
SELECT (
CAST (TO_TIMESTAMP ('2/2/2010 9:53:15.832 PM', 'mm/dd/yyyy hh:mi:ss.ff pm') AS DATE)
- CAST (TO_TIMESTAMP ('2/2/2010 9:53:14.432 PM', 'mm/dd/yyyy hh:mi:ss.ff pm') AS DATE)
* 86400 x
FROM DUAL
X
2
A more exact answer would use, to_char and to_date to convert :
SELECT (
TO_DATE (TO_CHAR (TO_TIMESTAMP ('2/2/2010 9:53:15.832 PM', 'mm/dd/yyyy hh:mi:ss.ff pm'),
'mm/dd/yyyy hh:mi:ss pm'),
'mm/dd/yyyy hh:mi:ss pm')
- TO_DATE (TO_CHAR (TO_TIMESTAMP ('2/2/2010 9:53:14.432 PM', 'mm/dd/yyyy hh:mi:ss.ff pm'),
'mm/dd/yyyy hh:mi:ss pm'),
'mm/dd/yyyy hh:mi:ss pm')
* 86400 x
FROM DUAL
X
1
Edit:
Massimo Ruocchio's answer actually works better.
-AC
Edited by: user12026137 on Feb 9, 2010 12:45 PM