title: Rows getting deleted when i update the timestamp?
body: <p>I thought this was fairly simple. I need to update four rows with a certain user_id parameter(say 'XYZ' such that the time values in the timestamps are reset to 12 am. </p>
  
  <p>I have 4 rows with this user_id in that table. </p>
  
  <p>I run the following query:</p>
  
  <pre><code>update table_to_be_updated
  set table_timestamp = to_timestamp(to_date(table_timestamp , 'yyyy/mm/dd'), 'YYYY-MM-DD HH24:MI:SS')
      where user_id = 'XYZ';
  </code></pre>
  
  <p>The query runs fine. Next, I try selecting all rows that have <code>user_id = 'XYZ'</code>, and the rows are gone! Can someone help with that is going wrong? I cannot see the rows in the select unless i rollback. </p>