title: Generating unique number in Oracle
body: <p>I have a table containing following column </p>
  
  <pre><code> APP_ID(VarChar),USER_ID(VarChar), ROLE_ID(Number),....
     app1                user1          3
     app1                user2          3
     app2                user2          4
     app2                user3          3
     app3                user1          7
  </code></pre>
  
  <p>As you can see there is no ID field and i cannot add it. </p>
  
  <p>if i use below query it is giving me unique and same number every time i use below query</p>
  
  <pre><code>SELECT owa_opt_lock.checksum(a.APP_ID || a.USER_ID || a.ROLE_ID) as ID 
  </code></pre>
  
  <p>I want to know it is safe to use this. </p>