Thread: Extracting time from timestamp

Extracting time from timestamp

From

"Shridhar Daithankar"

Date:

20 March 2003, 14:06:01

Hi,

I know this is rather stupid but still,

I have a table which has a timestamp field in it and I need to get only time
part of it. i.e. HH:MI format.

So far I tried,

phd=# select to_timestamp( to_char(stime,'HH24:MI'),'HH24:MI') from bookings;
      to_timestamp
------------------------
 0001-01-01 04:30:00 BC
 0001-01-01 04:30:00 BC
 0001-01-01 04:30:00 BC
(3 rows)


I don't know where that BC crept in. It does not show up when I just select
stime from bookings;

I also tried

phd=# select timestamp to_char(stime,'HH24:MI'),'HH24:MI' from bookings;
ERROR:  parser: parse error at or near "to_char" at character 18

To me that looks like casting a text returned by to_char to timestamp. This
casting should work if I infer from things like to_char(timestamp
'now','HH12:MI:SS') mentioned in postgresql manual(Data type formatting
function, section 6.7).

Being very stupid, is there any more efficient way of doing this?

TIA..

 Shridhar

Re: Extracting time from timestamp

From

"Shridhar Daithankar"

Date:

21 March 2003, 01:28:50

On Friday 21 Mar 2003 12:04 am, Darren Ferguson wrote:
> If the field is definately a timestamp field just do the following
>
> SELECT TO_CHAR(stime,'HH24:MI') FROM bookings;

Problem is I want timestamp out of it, not char. representation because I have
to compare quite a few of them. That's where I am stuck..

 Shridhar

Re: Extracting time from timestamp

From

"Shridhar Daithankar"

Date:

21 March 2003, 03:57:03

On Thursday 20 Mar 2003 9:36 pm, Shridhar
Daithankar<shridhar_daithankar@persistent.co.in> wrote:
> I know this is rather stupid but still,
>
> I have a table which has a timestamp field in it and I need to get only
> time part of it. i.e. HH:MI format.

After much of RTFm( \df in psql in fact ), I found the solution. It is
timetz(abstime(timestamp)).

Well, timezone is OK with me but if somebody needs no timezones, then it is
still screwed though..

Further more, \df I find following output

 time without time zone      | pg_catalog | time| abstime
 time without time zone      | pg_catalog | time| interval
 time without time zone      | pg_catalog | time| text
 time without time zone      | pg_catalog | time| time with time zone
 time without time zone      | pg_catalog | time| time without time zone,
integer
 time without time zone      | pg_catalog | time| timestamp with time zone
 time without time zone      | pg_catalog | time| timestamp without time zone

I don't found these functions working as they expected. e.g.

phd=# select time(abstime(timestamp 'now')) from bookings;
ERROR:  parser: parse error at or near "abstime" at character 13
phd=# select time(timestamp 'now') from bookings;
ERROR:  parser: parse error at or near "timestamp" at character 13
phd=# select version();
                               version
---------------------------------------------------------------------
 PostgreSQL 7.3.2 on i386-portbld-freebsd4.7, compiled by GCC 2.95.4
(1 row)

That goes for any timestamp value I presume. Is this a bug or am I
misinterpreting the information?

 Shridhar

Re: [HACKERS] Extracting time from timestamp

From

"Shridhar Daithankar"

Date:

21 March 2003, 04:12:49

On Friday 21 Mar 2003 11:38 am, Christopher Kings-Lynne wrote:
> > phd=# select time(abstime(timestamp 'now')) from bookings;
> > ERROR:  parser: parse error at or near "abstime" at character 13
> > phd=# select time(timestamp 'now') from bookings;
> > ERROR:  parser: parse error at or near "timestamp" at character 13
> > phd=# select version();
> >                                version
>
> Try:
>
> select "time"(abstime(timestamp 'now')) from bookings;
> select "time"(timestamp 'now') from bookings;

First of all, thanks, it worked..

And What's so holy about "" if it is a function?

That was bummer, I admit.. Spent almost a day on it..

 Shridhar

Re: Extracting time from timestamp

From

Darren Ferguson

Date:

22 March 2003, 04:11:08

If the field is definately a timestamp field just do the following

SELECT TO_CHAR(stime,'HH24:MI') FROM bookings;

This will give you the desired answer

Darren

On Thu, 20 Mar 2003, Shridhar Daithankar<shridhar_daithankar@persistent.co.in> wrote:

> Hi,
>
> I know this is rather stupid but still,
>
> I have a table which has a timestamp field in it and I need to get only time
> part of it. i.e. HH:MI format.
>
> So far I tried,
>
> phd=# select to_timestamp( to_char(stime,'HH24:MI'),'HH24:MI') from bookings;
>       to_timestamp
> ------------------------
>  0001-01-01 04:30:00 BC
>  0001-01-01 04:30:00 BC
>  0001-01-01 04:30:00 BC
> (3 rows)
>
>
> I don't know where that BC crept in. It does not show up when I just select
> stime from bookings;
>
> I also tried
>
> phd=# select timestamp to_char(stime,'HH24:MI'),'HH24:MI' from bookings;
> ERROR:  parser: parse error at or near "to_char" at character 18
>
> To me that looks like casting a text returned by to_char to timestamp. This
> casting should work if I infer from things like to_char(timestamp
> 'now','HH12:MI:SS') mentioned in postgresql manual(Data type formatting
> function, section 6.7).
>
> Being very stupid, is there any more efficient way of doing this?
>
> TIA..
>
>  Shridhar
>
>
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--
Darren Ferguson

Re: [HACKERS] Extracting time from timestamp

From

"Christopher Kings-Lynne"

Date:

22 March 2003, 04:11:16

> phd=# select time(abstime(timestamp 'now')) from bookings;
> ERROR:  parser: parse error at or near "abstime" at character 13
> phd=# select time(timestamp 'now') from bookings;
> ERROR:  parser: parse error at or near "timestamp" at character 13
> phd=# select version();
>                                version

Try:

select "time"(abstime(timestamp 'now')) from bookings;
select "time"(timestamp 'now') from bookings;

Chris

Re: [HACKERS] Extracting time from timestamp

From

Chris Gamache

Date:

23 March 2003, 14:01:12

Why not a cast?

template1=# select current_timestamp::time;
      time
-----------------
 11:24:22.004207
(1 row)

template1=# select current_timestamp::time(0);
   time
----------
 11:24:26
(1 row)


--- Christopher Kings-Lynne <chriskl@familyhealth.com.au> wrote:
> > phd=# select time(abstime(timestamp 'now')) from bookings;
> > ERROR:  parser: parse error at or near "abstime" at character 13
> > phd=# select time(timestamp 'now') from bookings;
> > ERROR:  parser: parse error at or near "timestamp" at character 13
> > phd=# select version();
> >                                version
>
> Try:
>
> select "time"(abstime(timestamp 'now')) from bookings;
> select "time"(timestamp 'now') from bookings;
>
> Chris
>
>
> ---------------------------(end of broadcast)---------------------------
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>
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