title: how to get record date wise descending and then give record which has no date- in sql
body: <p>i have a table named attendance_master 
  i have records like below:</p>
  
  <h2>        attendant_id |  inout_time            | name</h2>
  
  <pre><code>    1            |    NULL                | n1  
      2            |    NULL                | n2 
      3            |    2015-05-18 10:10:00 | n3 
      4            |    2015-05-19 10:05:00 | n4
      5            |    2015-05-18 10:07:00 | n5
      6            |    2015-05-18 12:03:00 | n6
  </code></pre>
  
  <p>now i want result like below:</p>
  
  <h2>        attendant_id |  inout_time            | name</h2>
  
  <pre><code>    4            |    2015-05-19 10:05:00 | n4
      6            |    2015-05-18 12:03:00 | n6
      3            |    2015-05-18 10:10:00 | n3 
      5            |    2015-05-18 10:07:00 | n5
      1            |    NULL                | n1  
      2            |    NULL                | n2 
  </code></pre>
  
  <p>my current query and result is like below:</p>
  
  <pre><code>  select * from attendance_master order by inout_time DESC
  </code></pre>
  
  <p>Note: i dont want to use union.</p>
  
  <h2>        attendant_id |  inout_time            | name</h2>
  
  <pre><code>    1            |    NULL                | n1  
      2            |    NULL                | n2 
      4            |    2015-05-19 10:05:00 | n4
      6            |    2015-05-18 12:03:00 | n6
      3            |    2015-05-18 10:10:00 | n3 
      5            |    2015-05-18 10:07:00 | n5
  </code></pre>