-- funzione per trasformare un text,char,varchar in un float...
-- CAST(text AS float);

drop function float8(text);
create function float8(text) returns float8 as
'declare
	f float8;
begin
        IF $1 ISNULL THEN
	    RETURN ''0'';
        ELSE
	    f:= trim($1);
            RETURN f;
        END IF;
 end;
' language 'plpgsql';

create table a (t text, c char(10), v varchar);
insert into a values ('1.2','1.3','1.4');
insert into a values ('1.2');
select cast(t as float), cast(c as float), cast(v as float) from a;
select * from a;
select cast('12' as float);
drop table a;