Re: Postgres 8 - problem: invalid input syntax for integer

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