How to create id with AUTO_INCREMENT on Oracle?

Question

It appears that there is no concept of AUTO_INCREMENT in Oracle, up until and including version 11g.

How can I create a column that behaves like auto increment in Or

Answer 1

This is how I did this on an existing table and column (named id):

UPDATE table SET id=ROWNUM;
DECLARE
  maxval NUMBER;
BEGIN
  SELECT MAX(id) INTO maxval FROM table;
  EXECUTE IMMEDIATE 'DROP SEQUENCE table_seq';
  EXECUTE IMMEDIATE 'CREATE SEQUENCE table_seq START WITH '|| TO_CHAR(TO_NUMBER(maxval)+1) ||' INCREMENT BY 1 NOMAXVALUE';
END;
CREATE TRIGGER table_trigger
  BEFORE INSERT ON table
  FOR EACH ROW
BEGIN
  :new.id := table_seq.NEXTVAL;
END;