title: order by clause in union statement
body: <p>I have some records coming from 4 tables and date is not the common field in all of them but I use 'as'. Now I need to order by date   </p>
  
  <pre><code>select id,convert(varchar(20), SoldDate,3) as Date from sale 
  union
  select id,convert(varchar(20), PaymentDate,3) as Date from purchase 
  union 
  select id,convert(varchar(20), PaymentClearedDate,3) as Date from payments 
  union 
  select id,convert(varchar(20), PaymentClearedDate,3) as Date from orders    
  order by Date desc
  </code></pre>
  
  <p>I need order by Date</p>