title: How to change default date,timestamp dataype for columns in oracle
body: <p>I have created a table in Oracle in which I have <code>KPI_START_DATE</code> column which is a Date datatype, and <code>KPI_START_TIME</code> which is a <code>TIMESTAMP</code> datatype. 
  Now I want to modify this date dataype for</p>
  
  <p><code>KPI_START_DATE</code> to <code>dd/mm/yyyy</code></p>
  
  <p>and </p>
  
  <p><code>KPI_START_TIME</code> to <code>HH:MI:SS</code>. </p>
  
  <p>So that user should always enter the date and time in this column in this proper format.</p>
  
  <p>I tried below query but its was giving error:</p>
  
  <pre><code>Alter table KPI_DEFINITION MODIFY(to_char(KPI_START_DATE,'dd/mm/yyyy') )
  </code></pre>