Re: [GENERAL] date comparisons
OK, so we have a bug. Thanks.
---
Chad Wagner wrote:
> On 2/3/07, Bruce Momjian <[EMAIL PROTECTED]> wrote:
> >
> >
> > Would someone please confirm that our behavior in the three queries
> > below matches Oracle's behavior?
>
>
> Here is output from Oracle:
>
> Connected to:
> Oracle Database 10g Enterprise Edition Release 10.2.0.2.0 - Production
> With the Partitioning, OLAP and Data Mining options
>
> SQL> alter session set nls_timestamp_format = '-MM-DD HH.MI.SSXFF AM';
>
> Session altered.
>
> SQL> select to_timestamp('January 2006', 'Month ') from dual;
>
> TO_TIMESTAMP('JANUARY2006','MONTH')
> ---
> 2006-01-01 12.00.00.0 AM
>
> SQL> select to_timestamp('January 2006', 'Month ') from dual;
>
> TO_TIMESTAMP('JANUARY2006','MONTH')
> ---
> 2006-01-01 12.00.00.0 AM
>
> SQL> select to_timestamp('January 2006', 'FMMonth ') from dual;
>
> TO_TIMESTAMP('JANUARY2006','FMMONTH')
> ---
> 2006-01-01 12.00.00.0 AM
--
Bruce Momjian [EMAIL PROTECTED]
EnterpriseDBhttp://www.enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
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Re: [GENERAL] date comparisons
On 2/3/07, Bruce Momjian <[EMAIL PROTECTED]> wrote:
Would someone please confirm that our behavior in the three queries
below matches Oracle's behavior?
Here is output from Oracle:
Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.2.0 - Production
With the Partitioning, OLAP and Data Mining options
SQL> alter session set nls_timestamp_format = '-MM-DD HH.MI.SSXFF AM';
Session altered.
SQL> select to_timestamp('January 2006', 'Month ') from dual;
TO_TIMESTAMP('JANUARY2006','MONTH')
---
2006-01-01 12.00.00.0 AM
SQL> select to_timestamp('January 2006', 'Month ') from dual;
TO_TIMESTAMP('JANUARY2006','MONTH')
---
2006-01-01 12.00.00.0 AM
SQL> select to_timestamp('January 2006', 'FMMonth ') from dual;
TO_TIMESTAMP('JANUARY2006','FMMONTH')
---
2006-01-01 12.00.00.0 AM
Re: [GENERAL] date comparisons
Would someone please confirm that our behavior in the three queries
below matches Oracle's behavior?
---
Tom Lane wrote:
> "Belinda M. Giardine" <[EMAIL PROTECTED]> writes:
> > Should it be this way?
>
> Well, to_timestamp() is apparently designed not to complain when the
> input doesn't match the format, which is not my idea of good behavior
> ... but your example is in fact wrong. 'Month' means a 9-character
> field, so you are short a couple of spaces.
>
> regression=# select to_timestamp('January 2006', 'Month ');
> to_timestamp
>
> 0006-01-01 00:00:00-05
> (1 row)
>
> regression=# select to_timestamp('January 2006', 'Month ');
> to_timestamp
>
> 2006-01-01 00:00:00-05
> (1 row)
>
> You probably want
>
> regression=# select to_timestamp('January 2006', 'FMMonth ');
> to_timestamp
>
> 2006-01-01 00:00:00-05
> (1 row)
>
> Or, as suggested upthread, forget to_timestamp and just use the native
> timestamp or date input conversion, which on the whole is a lot more
> robust (it *will* throw an error if it can't make sense of the input,
> unlike to_timestamp).
>
> regards, tom lane
>
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--
Bruce Momjian [EMAIL PROTECTED]
EnterpriseDBhttp://www.enterprisedb.com
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Re: [GENERAL] date comparisons
Richard Huxton writes: > The padding is on *input* too? Is this an Oracle compatibility "feature"? I assume so. If Oracle does not work like that, then it'd be a bug ... but the whole purpose of that function is to be Oracle-compatible, so we're sort of stuck doing what Oracle does. regards, tom lane ---(end of broadcast)--- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
Re: [GENERAL] date comparisons
Tom Lane wrote: "Belinda M. Giardine" <[EMAIL PROTECTED]> writes: Should it be this way? Well, to_timestamp() is apparently designed not to complain when the input doesn't match the format, which is not my idea of good behavior ... but your example is in fact wrong. 'Month' means a 9-character field, so you are short a couple of spaces. The padding is on *input* too? Is this an Oracle compatibility "feature"? -- Richard Huxton Archonet Ltd ---(end of broadcast)--- TIP 4: Have you searched our list archives? http://archives.postgresql.org/
Re: [GENERAL] date comparisons
On Tue, 12 Dec 2006, Tom Lane wrote:
> "Belinda M. Giardine" <[EMAIL PROTECTED]> writes:
> > Should it be this way?
>
> Well, to_timestamp() is apparently designed not to complain when the
> input doesn't match the format, which is not my idea of good behavior
> ... but your example is in fact wrong. 'Month' means a 9-character
> field, so you are short a couple of spaces.
>
> regression=# select to_timestamp('January 2006', 'Month ');
> to_timestamp
>
> 0006-01-01 00:00:00-05
> (1 row)
>
> regression=# select to_timestamp('January 2006', 'Month ');
> to_timestamp
>
> 2006-01-01 00:00:00-05
> (1 row)
>
> You probably want
>
> regression=# select to_timestamp('January 2006', 'FMMonth ');
> to_timestamp
>
> 2006-01-01 00:00:00-05
> (1 row)
Thanks. I wanted to understand the reason for my attempt not working no
matter which method I used in the end. Help to prevent future errors.
>
> Or, as suggested upthread, forget to_timestamp and just use the native
> timestamp or date input conversion, which on the whole is a lot more
> robust (it *will* throw an error if it can't make sense of the input,
> unlike to_timestamp).
>
> regards, tom lane
Good to know.
Belinda
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Re: [GENERAL] date comparisons
"Belinda M. Giardine" <[EMAIL PROTECTED]> writes:
> Should it be this way?
Well, to_timestamp() is apparently designed not to complain when the
input doesn't match the format, which is not my idea of good behavior
... but your example is in fact wrong. 'Month' means a 9-character
field, so you are short a couple of spaces.
regression=# select to_timestamp('January 2006', 'Month ');
to_timestamp
0006-01-01 00:00:00-05
(1 row)
regression=# select to_timestamp('January 2006', 'Month ');
to_timestamp
2006-01-01 00:00:00-05
(1 row)
You probably want
regression=# select to_timestamp('January 2006', 'FMMonth ');
to_timestamp
2006-01-01 00:00:00-05
(1 row)
Or, as suggested upthread, forget to_timestamp and just use the native
timestamp or date input conversion, which on the whole is a lot more
robust (it *will* throw an error if it can't make sense of the input,
unlike to_timestamp).
regards, tom lane
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Re: [GENERAL] date comparisons
Belinda M. Giardine wrote:
Thanks that works. But I am trying to understand why the others did not,
especially my first attempt. Further testing shows that
select id, date_entered from main_table where
date_entered >= to_timestamp('2006 January', ' Month');
works, but
select id, date_entered from main_table where
date_entered >= to_timestamp('January 2006', 'Month ');
does not. The order of the fields in the to_timestamp function changes
the timestamp produced. Should it be this way?
No. Good testing, you've found a bug. Seems to be a problem with the
"Month" formatting if there's more fields after it.
hbvar=# select to_timestamp('January 2006', 'Month ');
to_timestamp
0006-01-01 00:00:00-05
(1 row)
hbvar=# select to_timestamp('2006 January', ' Month');
to_timestamp
2006-01-01 00:00:00-05
(1 row)
SELECT to_timestamp('January 22 2006','Month DD ');
to_timestamp
0005-06-28 00:00:00+00
(1 row)
SELECT to_timestamp('Jan 22 2006','Mon DD ');
to_timestamp
2006-01-22 00:00:00+00
(1 row)
If you report this bug using the form below, I'm sure one of the
developers will have a patch out shortly.
http://www.postgresql.org/support/submitbug
Good catch!
--
Richard Huxton
Archonet Ltd
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Re: [GENERAL] date comparisons
On Tue, 12 Dec 2006, Erik Jones wrote:
> Belinda M. Giardine wrote:
> > This should be simple but I am missing something. I am trying to extract
> > all records entered after a given date. The table has a field
> > date_entered which is a timestamp. In this particular case I am not
> > worried about time.
> >
> > I have tried:
> > select id from main_table where
> > date_entered > to_timestamp('January 2006', 'Month ');
> >
> > select id from main_table where
> > (to_timestamp('January 2006', 'Month '), now()) overlaps (date_entered,
> > date_entered);
> >
> > Both of these return all the rows in the table. Half of the rows are
> > dated 2000-06-22 12:00:00.
> >
> > PostgreSQL version 8.1.4
> >
> I think people often make date comparisons too difficult in postgres.
>
> select id
> from main_table
> where date_entered >= '2006-01-01';
>
> There are built in conversions for formatted date strings.
>
> --
> erik jones <[EMAIL PROTECTED]>
> software development
> emma(r)
>
Thanks that works. But I am trying to understand why the others did not,
especially my first attempt. Further testing shows that
select id, date_entered from main_table where
date_entered >= to_timestamp('2006 January', ' Month');
works, but
select id, date_entered from main_table where
date_entered >= to_timestamp('January 2006', 'Month ');
does not. The order of the fields in the to_timestamp function changes
the timestamp produced. Should it be this way?
hbvar=# select to_timestamp('January 2006', 'Month ');
to_timestamp
0006-01-01 00:00:00-05
(1 row)
hbvar=# select to_timestamp('2006 January', ' Month');
to_timestamp
2006-01-01 00:00:00-05
(1 row)
Belinda
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Re: [GENERAL] date comparisons
Belinda M. Giardine wrote:
This should be simple but I am missing something. I am trying to extract
all records entered after a given date. The table has a field
date_entered which is a timestamp. In this particular case I am not
worried about time.
I have tried:
select id from main_table where
date_entered > to_timestamp('January 2006', 'Month ');
select id from main_table where
(to_timestamp('January 2006', 'Month '), now()) overlaps (date_entered,
date_entered);
Both of these return all the rows in the table. Half of the rows are
dated 2000-06-22 12:00:00.
PostgreSQL version 8.1.4
I think people often make date comparisons too difficult in postgres.
select id
from main_table
where date_entered >= '2006-01-01';
There are built in conversions for formatted date strings.
--
erik jones <[EMAIL PROTECTED]>
software development
emma(r)
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match
[GENERAL] date comparisons
This should be simple but I am missing something. I am trying to extract
all records entered after a given date. The table has a field
date_entered which is a timestamp. In this particular case I am not
worried about time.
I have tried:
select id from main_table where
date_entered > to_timestamp('January 2006', 'Month ');
select id from main_table where
(to_timestamp('January 2006', 'Month '), now()) overlaps (date_entered,
date_entered);
Both of these return all the rows in the table. Half of the rows are
dated 2000-06-22 12:00:00.
PostgreSQL version 8.1.4
What am I missing?
Belinda
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