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
functionsthat 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