>Edward,
>If dbf(mycursor) is a table (temporal but a table until i close cursor). If i can open it exclusively (more or less) cause i can index it after 'use dbf() again in 0'. ¿Why can't i use 'alter table...'?
>how can you modify initial select to get a general field in cursor? and to get a numeric(6, 3) field you must include a value like 134.567 in select clause and after replace all with 0? That's not a very fine way, isn't it?

I said, 'probably you can't use ALTER TABLE. If you tried and it works, so good for you, anyway I cannot be blamed for some VFP command syntax rules.
In regard to SELECT: you can always add dummy field there to get new numeric:
Select *,000.000 as dummy from table1 into cursor tmp
General field is a little bit more complicated, but not too much:
create cursor tmp (genfield G NULL)
insert into tmp values(.NULL.)
select table2.*,genfield from table2,tmp into cursor tmp1