title: how to use dbms_scheduler to run the job every 30 minutes
body: <p>I am using oracle DB ,  now as i am monitoring the performance of oracle DB which is connected to my java application , so rite now i have to monitor the count of active connections in DB at regular intervals lets say after every 30 minutes  below is the query which return me the count of active users along with there name and count </p>
  
  <pre><code>select osuser, count(osuser) as active_conn_count 
  from v$session 
  group by osuser 
  order by active_conn_count desc
  </code></pre>
  
  <p>now please  advise how can i make an schedule a job in scheduler in oracle DB itself that will get triggered at every 30 minutes .</p>