Found an answer for question number 2:

https://metalink2.oracle.com/metalink/plsql/f?p=130:14:2551972738979005909::::p14_database_id,p14_docid,p14_show_header,p14_show_help,p14_black_frame,p14_font:NOT,466228.1,1,0,1,helvetica

Thanks for the input, Lynn. It doesn't appear to be a problem to mismatch those column definitions, based on some tests I did, though:

create table test_n_id2

(

n_idvarchar(20)

)

----------------------------

insert into test_n_id2

select

national_id

from...