Re: ALTER TABLE ( smallinto -> boolean ) ...

Tom Lane wrote:

>"Marc G. Fournier" <scrappy@postgresql.org> writes:
>  
>
>>On Mon, 29 Aug 2005, Tom Lane wrote:
>>    
>>
>>>No, because there's no built-in cast from smallint to bool.
>>>      
>>>
>
>  
>
>>'k, I just took a read through the "CREATE CAST" man page, and don't think 
>>I can use that for this,
>>    
>>
>
>Sure you can.  Make a SQL or PLPGSQL function that does the conversion
>you want and then create a cast using it.
>  
>

That probably won't help him much with "values(0)":

andrew=# create function ibool(smallint) returns boolean language sql as 
$$ select $1 <> 0 $$;
CREATE FUNCTION
andrew=# create cast (smallint as boolean) with function ibool(smallint) 
as implicit;
CREATE CAST
andrew=# insert into foobool values(0);
ERROR:  column "x" is of type boolean but expression is of type integer
HINT:  You will need to rewrite or cast the expression.

Is there a way to make the builtin int to bool cast implicit?

cheers


andrew