APEX don't allow modify rows in columns which are Primary Key ?

Question

I have tables:
http://img508.imageshack.us/my.php?image=21269582oe8.jpg
book(id_book - "Primary Key", title, year); book_author(id_book - "Primary Key", id_author - "Primary Key"); author(id_author - "Primary Key", name)
I have created a new page -> Form -> Tabular Form for table 'author' because I would like to add new authors, modify and delete. During creating this page I have choosen column 'id_author' as 'primary key column 1' and everything is OK (I can't modify column 'id_author' - this column is autoincrement and I can modify column 'name').
BUT I have also created a new page -> Form -> Tabular for table 'book_author' because I would like to write numbers as id_book and id_author, modify and delete them (so add relations between tables: book, book_author and author). During creating this page I have choosen column 'id_book' as 'primary key column 1' and 'id_author' as 'primary key column 2'. And on website I can't modify (edit) these fields. And I can't also add new row because I see in each column in new row: (null).
http://img444.imageshack.us/my.php?image=11324615yk9.jpg
APEX don't allow modify rows in columns which are Primary Key ? This is stupid....... What can I do ?
Edited by: user10731158 on 2008-12-20 11:40

Answer 1

Single-column and non-meaningful so you never want to update them. In the case of your example, you would need to add an ID column to the book_author intersection table. Honestly, I was so blown away (and pleasantly surprised) by the lack of rebuttal and the "thx" that I went ahead and put together an example of how I would define the book_author table:
create table  book_author
   (id varchar2(32),
    book_id varchar2(32),
     author_id varchar2(32),
     modified_on     date,
     modified_by varchar2(255),
     constraint book_author_pk primary key (id),
     constraint book_auth_book_fk foreign key (book_id) references books(id),
     constraint book_auth_author_fk foreign key (author_id) references authors(id)
create unique index book_author_uq on book_author (book_id,author_id)
create or replace trigger  biu_book_author before insert or update on book_author
for each row
begin     
     if inserting then
          :new.id := sys_guid();
     end if;
     modified_on := sysdate;
     modified_by := nvl(v('APP_USER'),user);
end;
/Good luck,
Tyler