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
