title: mysql order by select -- possible?
body: <p>Here is my table setup:</p>
  
  <pre><code>mysql&gt; describe a;
  +-------+------------+------+-----+---------+----------------+
  | Field | Type       | Null | Key | Default | Extra          |
  +-------+------------+------+-----+---------+----------------+
  | id    | int(11)    | NO   | PRI | NULL    | auto_increment | 
  | x     | int(11)    | YES  |     | NULL    |                | 
  | y     | varchar(1) | YES  |     | NULL    |                | 
  +-------+------------+------+-----+---------+----------------+
  3 rows in set (0.01 sec)
  
  mysql&gt; describe b;
  +-------+------------+------+-----+---------+----------------+
  | Field | Type       | Null | Key | Default | Extra          |
  +-------+------------+------+-----+---------+----------------+
  | id    | int(11)    | NO   | PRI | NULL    | auto_increment | 
  | a     | int(11)    | NO   |     | NULL    |                | 
  | z     | varchar(1) | YES  |     | NULL    |                | 
  +-------+------------+------+-----+---------+----------------+
  3 rows in set (0.01 sec)
  
  mysql&gt; select * from a;
  +----+------+------+
  | id | x    | y    |
  +----+------+------+
  |  1 |    1 | a    | 
  |  2 |    2 | b    | 
  |  3 |    3 | c    | 
  |  4 |    4 | d    | 
  +----+------+------+
  4 rows in set (0.01 sec)
  
  mysql&gt; select * from b;
  +----+---+------+
  | id | a | z    |
  +----+---+------+
  |  1 | 3 | q    | 
  |  2 | 2 | a    | 
  |  3 | 1 | u    | 
  |  4 | 4 | x    | 
  +----+---+------+
  4 rows in set (0.01 sec)
  </code></pre>
  
  <p>Here's what I want to do:</p>
  
  <pre><code>mysql&gt; select a.* from a, b where a.id = b.a order by b.z;
  +----+------+------+
  | id | x    | y    |
  +----+------+------+
  |  2 |    2 | b    | 
  |  3 |    3 | c    | 
  |  1 |    1 | a    | 
  |  4 |    4 | d    | 
  +----+------+------+
  4 rows in set (0.00 sec)
  </code></pre>
  
  <p>However, I want to use a syntax like "SELECT * FROM a ORDER BY (SELECT a FROM b ORDER BY z)".</p>
  
  <p>Is this possible?</p>