title: Using Date_add() or add_time() function in create table itself
body: <p>How to create an attribute which takes current timestamp and adds some mins to it (eg: add 30 mins) in create table itself in MySql.</p>
  
  <pre><code>create table (order_time timestamp default current_timestamp,
                est_time timestamp default current_timestamp date_add(min,30));
  
  shows syntax error
  </code></pre>
  
  <p>or while altering</p>
  
  <pre><code>alter table  orders modify est_time timestamp date_add(order_time,interval 30 min);
  
  create table (order_time timestamp default current_timestamp,
                est_time timestamp default current_timestamp date_add(min,30));
  </code></pre>