title: Incorrect usage of UNION and ORDER BY?
body: <p>how can i use <strong>union</strong> and <strong>order by</strong> in mysql ?</p>
  
  <pre><code>select * from _member_facebook 
  inner join _member_pts 
  ON _member_facebook._fb_owner=_member_pts._username 
  where _member_facebook._promote_point = 9 
  ORDER BY RAND() limit 2 
  UNION ALL
  select * from _member_facebook 
  inner join _member_pts 
  ON _member_facebook._fb_owner=_member_pts._username 
  where _member_facebook._promote_point = 8 limit 3
  </code></pre>
  
  <p>give me error </p>
  
  <pre><code>#1221 - Incorrect usage of UNION and ORDER BY
  </code></pre>
  
  <p>any one can help ?</p>