title: Oracle 11g Select Distinct Not Unique
body: <p>I kinda lost with this simple query</p>
  
  <p>Below is the query with date (<strong>SERVICE_DATE</strong>):</p>
  
  <pre><code>SELECT DISTINCT JOB_ID,
         SERVICE_DATE,
         GRAND_TOTAL,
         TYPE_INSERT,
         PAYMENT_ID
  FROM   TBL_XXX
  WHERE  USER_ID = 100
         AND PAYMENT_ID &lt;&gt; 0
  ORDER  BY JOB_ID DESC;
  </code></pre>
  
  <p>And I got this result:</p>
  
  <pre><code>467 18/10/2012  16  Upload  527811
  467 18/10/2012  16  Upload  527811
  466 18/10/2012  4   Key-In  527806
  465 18/10/2012  4   Key-In  527804
  464 17/10/2012  24  Upload  527784
  464 17/10/2012  24  Upload  527784
  464 17/10/2012  24  Upload  527784
  </code></pre>
  
  <p>while this query without date (<strong>SERVICE_DATE</strong>)</p>
  
  <pre><code>SELECT DISTINCT JOB_ID,
         GRAND_TOTAL,
         TYPE_INSERT,
         PAYMENT_ID
  FROM   TBL_XXX
  WHERE  USER_ID = 100
         AND PAYMENT_ID &lt;&gt; 0
  ORDER  BY JOB_ID DESC;
  </code></pre>
  
  <p>Result:</p>
  
  <pre><code>467 16  Upload  527811
  466 4   Key-In  527806
  465 4   Key-In  527804
  464 24  Upload  527784
  </code></pre>
  
  <p>what Im missing here ?</p>