Add an autoincrement column to a populated table

Question

Hi I have a large table say test. I want to add a new column and populate this column with row number. How do I do it?
I was thinking that I could create a new table with id as column and populate it with numbers from 1 to total row number of the test table. Then merge the two table on columns. How do I do this?
Edited by: user10151006 on May 26, 2009 9:03 AM

Answer 1

Why do you want to change the sequence on an update?
Can't you do something like this:
SQL> create table t as select * from all_objects;
Table created.
SQL> alter table t add (seq_col number);
Table altered.
SQL> create sequence t_seq;
Sequence created.
SQL> update t
  2  set    seq_col = t_seq.nextval;
53029 rows updated.
SQL> commit;
Commit complete.
SQL> create or replace
  2  trigger t_trig
  3  before insert
  4  on t
  5  for each row
  6  declare
  7     l_num number;
  8  begin
  9     select t_seq.nextval
10     into   l_num
11     from   dual;
12
13     :new.seq_col := l_num;
14  end;
15  /
Trigger created.
SQL> insert into t (owner, object_id, object_name, created, last_ddl_time) values ('ME',999,'BLAH',sysdate,sysdate);
SQL> select owner, object_name, seq_col from t where object_name = 'BLAH';
OWNER                          OBJECT_NAME                                 SEQ_COL
ME                             BLAH                                          53033