从10g开始，DBMS_SCHEDULER 逐步会替换掉 DBMS_JOB，下面是它们的区别及其替换的理由。

DBMS_JOB has been around forever, and now it is deprecated. Although DBMS_JOB still exists in 10g and 11g, but only for backward compatibility. No new features are being added to dbms_job and you will likely quickly run into its limitations. Oracle recommends the use of DBMS_SCHEDULER in releases 10g and up. DBMS_SCHEDULER is a much more robust package and fully-featured than DBMS_JOB. To use the DBMS_SCHEDULER package a user must be granted the CREATE JOB privilege.

DBMS_SCHEDULER includes the following features that DBMS_JOB does not have :

• logging of job runs (job history)
• simple but powerful scheduling syntax (similar to but more powerful than cron syntax)
• running of jobs outside of the database on the operating system
• resource management between different classes of jobs
• use of job arguments including passing of objects into stored procedures
• privilege-based security model for jobs
• naming of jobs and comments in jobs
• stored, reusable schedules

Features in releases after 10g Release 1 include :

• dependencies between job units (10gR2 and up)
• scheduling based on financial calendars and fiscal quarters (10gR2 and up)
• event based jobs which run when an event is received (10gR2 and up)
• running of jobs on remote machines (11gR1 and up)
• e-mail notifications on job events of interest (10gR2 and up)
• starting a job based on arrival of a file (10gR2 and up)

Here simple comparison for the codes :

• Old using DBMS_JOB scheduler.VARIABLE l_job NUMBER;
  BEGIN
  DBMS_JOB.submit (
  job => :l_job,
  what => ‘BEGIN NULL; /* code to execute*/ END;’,
  next_date => SYSDATE,
  interval => ‘SYSDATE + 1 /* 1 Day */’);COMMIT;
  END;
  /
  PRINT l_job
• New with DBMS_SCHEDULER scheduler.BEGIN
  DBMS_SCHEDULER.create_job (
  job_name => ‘dummy_job’,
  job_type => ‘PLSQL_BLOCK’,
  job_action => ‘BEGIN NULL; /* code to execute */ END;’,
  start_date => SYSTIMESTAMP,
  repeat_interval => ‘SYSTIMESTAMP + 1 /* 1 Day */’);
  END;
  /

After replace DBMS_JOB with DBMS_SCHEDULER for all jobs successful, the job_queue_processes parameter can now be set to zero.

SQL> alter system set job_queue_processes=0;

There is also a forum dedicated to questions about dbms_scheduler here : http://forums.oracle.com/forums/forum.jspa?forumID=193