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Postgres 8 - problem: invalid input syntax for integer
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* Postgres 8 - problem: invalid input syntax for integer
@ 2005-02-23 10:19 mauro <bertolima@yahoo.it>
  2005-02-24 08:14 ` Re: Postgres 8 - problem: invalid input syntax for integer Richard Huxton <dev@archonet.com>
  0 siblings, 1 reply; 4+ messages in thread

From: bertolima@yahoo.it @ 2005-02-23 10:19 UTC (permalink / raw)
  To: pgsql-sql

Hi, In previous version di Postgres (7.2) I used this table:
CREATE TABLE tablename (id serial, field int1, field2 text);

Now this query work:
UPDATE tablename SET field1=''; (NOTE: implicit conversion to 0)
UPDATE tablename SET field2='';

(this cause of simple code-generation query - I don't know what's
field type)

Now in postgres 8 this don't work. 
Why ?(ok, it's the ufficial documentation but I don't understand...
why? it's so comfortable!)
Can someone help me to create a CAST to re-use this feature?
Thank you! Mauro



^ permalink  raw  reply  [nested|flat] 4+ messages in thread

* Re: Postgres 8 - problem: invalid input syntax for integer
  2005-02-23 10:19 Postgres 8 - problem: invalid input syntax for integer mauro <bertolima@yahoo.it>
@ 2005-02-24 08:14 ` Richard Huxton <dev@archonet.com>
  2005-02-24 15:04   ` Re: Postgres 8 - problem: invalid input syntax for integer mauro <bertolima@yahoo.it>
  0 siblings, 1 reply; 4+ messages in thread

From: Richard Huxton @ 2005-02-24 08:14 UTC (permalink / raw)
  To: mauro <bertolima@yahoo.it>; +Cc: pgsql-sql

mauro wrote:
> Hi, In previous version di Postgres (7.2) I used this table:
> CREATE TABLE tablename (id serial, field int1, field2 text);
> 
> Now this query work:
> UPDATE tablename SET field1=''; (NOTE: implicit conversion to 0)
> UPDATE tablename SET field2='';
> 
> (this cause of simple code-generation query - I don't know what's
> field type)

Know your field-types. If you don't know what they are, you can't handle 
errors elegantly anyway.

> Now in postgres 8 this don't work. 
> Why ?(ok, it's the ufficial documentation but I don't understand...
> why? it's so comfortable!)

What number does '' represent?
Does that mean a string of '/2' should equal your number divided by two? 
If not, why not?
Who is providing an empty string where you've asked for a number, and 
why not trap this error (or store a NULL)?

> Can someone help me to create a CAST to re-use this feature?

Well, you could create a function:
CREATE FUNCTION empty_string_is_zero(text) RETURNS integer AS '
   SELECT CASE
     WHEN $1='''' THEN 0
     ELSE $1::integer
   END;
' LANGUAGE SQL;

UPDATE my_table SET myfield=empty_string_is_zero('');

HTH
--
   Richard Huxton
   Archonet Ltd



^ permalink  raw  reply  [nested|flat] 4+ messages in thread

* Re: Postgres 8 - problem: invalid input syntax for integer
  2005-02-23 10:19 Postgres 8 - problem: invalid input syntax for integer mauro <bertolima@yahoo.it>
  2005-02-24 08:14 ` Re: Postgres 8 - problem: invalid input syntax for integer Richard Huxton <dev@archonet.com>
@ 2005-02-24 15:04   ` mauro <bertolima@yahoo.it>
  2005-02-28 09:34     ` Re: Postgres 8 - problem: invalid input syntax for integer Richard Huxton <dev@archonet.com>
  0 siblings, 1 reply; 4+ messages in thread

From: bertolima@yahoo.it @ 2005-02-24 15:04 UTC (permalink / raw)
  To: pgsql-sql

> What number does '' represent?
'No response' value...
> Does that mean a string of '/2' should equal your number divided by two? 
right, but it is never required.
> If not, why not?
because I use it to GROUP BY values.
> Who is providing an empty string where you've asked for a number, and 
> why not trap this error (or store a NULL)?
You are certainly right. My problem concerns the compatibility of code
among postgres 8 and 7.2 that I wanted to maintain. The existing code
(data analysis) exploits the particularity that the null ('') becomes
0 (ok, no comment :) ) logically wrong but practically perfect!

[...CAST CODE...]

Thank you for the explicit-cast code, but I want reproduce it in
'database level' so I don't use explicit cast but IMPLICIT; everytime
updating integer fields with '' values it cast to (0 or NULL).

Best regards, Mauro



^ permalink  raw  reply  [nested|flat] 4+ messages in thread

* Re: Postgres 8 - problem: invalid input syntax for integer
  2005-02-23 10:19 Postgres 8 - problem: invalid input syntax for integer mauro <bertolima@yahoo.it>
  2005-02-24 08:14 ` Re: Postgres 8 - problem: invalid input syntax for integer Richard Huxton <dev@archonet.com>
  2005-02-24 15:04   ` Re: Postgres 8 - problem: invalid input syntax for integer mauro <bertolima@yahoo.it>
@ 2005-02-28 09:34     ` Richard Huxton <dev@archonet.com>
  0 siblings, 0 replies; 4+ messages in thread

From: Richard Huxton @ 2005-02-28 09:34 UTC (permalink / raw)
  To: mauro <bertolima@yahoo.it>; +Cc: pgsql-sql

mauro wrote:
>>What number does '' represent?
> 
> 'No response' value...

Would've been better to have a genuine response_provided flag, but then 
you obviously know that.

>>Who is providing an empty string where you've asked for a number, and 
>>why not trap this error (or store a NULL)?
> 
> You are certainly right. My problem concerns the compatibility of code
> among postgres 8 and 7.2 that I wanted to maintain. The existing code
> (data analysis) exploits the particularity that the null ('') becomes
> 0 (ok, no comment :) ) logically wrong but practically perfect!

Your best choice is probably to tweak your application and translate '' 
to NULL? Then you could add a before trigger to the table to replace 
NULL with 0.

> [...CAST CODE...]
> 
> Thank you for the explicit-cast code, but I want reproduce it in
> 'database level' so I don't use explicit cast but IMPLICIT; everytime
> updating integer fields with '' values it cast to (0 or NULL).

If you can't do the above, you've got three options:
  1. Stay with PG version 7.2
  2. Write your own type, with in/out functions that map '' to 0
  3. Hack the code to replace the ''=>0 conversion - you could probably 
identify the old code from CVS.

Obviously the null+trigger option is better than these three. Of these 
three though, number 2 is probably the cleanest solution.
--
   Richard Huxton
   Archonet Ltd



^ permalink  raw  reply  [nested|flat] 4+ messages in thread


end of thread, other threads:[~2005-02-28 09:34 UTC | newest]

Thread overview: 4+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2005-02-23 10:19 Postgres 8 - problem: invalid input syntax for integer mauro <bertolima@yahoo.it>
2005-02-24 08:14 ` Richard Huxton <dev@archonet.com>
2005-02-24 15:04   ` mauro <bertolima@yahoo.it>
2005-02-28 09:34     ` Richard Huxton <dev@archonet.com>

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