I have a table set up with a few fields

CREATE TABLE "books"
( "ISBN" VARCHAR2(20) NOT NULL ENABLE,
"Title" VARCHAR2(50) NOT NULL ENABLE,
"Author" VARCHAR2(100) NOT NULL ENABLE,
"Publisher" VARCHAR2(100) NOT NULL ENABLE,
"Subject" VARCHAR2(30),
"Pages" NUMBER
)

When I try to add a row using Insert Row from the Orfacle Database
Express Edition Web Page,
the ISBN, which is supposed to be unique per book (so I want to use it
as a Primary Key once the table is loaded) somehow changes to a
different value after I am done adding a new row. There are no
constraints or indexes on the table as I removed them thinking they
might be the cause of my problem. However I have had no luck in
identifying the cause. So I have to edit each row after I add it and
change the ISBN to the value I originally typed in. This seems a bit
odd to me so I am wondering what I can look at or check to see what *I*
have done wrong.