SQL & PL/SQL

Oracle version: Enterprise Edition 11g - 11.2.0.1.0
OS: Redhat Linux Enterprise Edition 5.0



Dear all,


I have a question about NOT NULL columns in oracle tables and I would appreciate if you could kindly help me with this problem.

I have the following table

CREATE TABLE ARTICLES
(
    artid                VARCHAR2(20),
    lbl                  VARCHAR2(100)        NOT NULL,
    cmporder             VARCHAR2(30)         NOT NULL      
)

ALTER TABLE ARTICLES ADD CONSTRAINT PK_ARTICLES PRIMARY KEY(artid);

It's about a year that I have this table but recently the data model has changed and the third column in the table is no more mandatory, therefore NULL values for the third column cmporder are allowed. What I would like to know is that whether it is possible to change the table definition (for example by using some ALTER statement) in order to remove the "NOT NULL" constraint from the third column? In this way I can conserve the 2 million lines which are already in the table and avoiding to do a bakup before dropping and recreating the table.


Thanks in advance,

Kind Regards,
Dariyoosh