PL/SQL :: Update Entire Table

If i have a table, my_table, with 20 columns, and i have something like:

declare
...
begin
  for r in (select * from my_table) loop
    insert into my_table (...) values (...)
  end loop;
end;

So, I want to insert a row into that table, with values for all columns being those returned by the for loop, but without a column (i'm giving the value for that column).For example, the first 19 rows should contain the values from the currently record in 'for.. loop', and the last column to contain a static value.Is it possible to do this, without specifying in the 'values' clause, something like (r.col1, r.col2, .... r.col19, 'G')? meaning other insert method.