title: order by with multiply custom name in brackets failed
body: <p>It failed when I put the column name in brackets:</p>
  
  <pre><code>select id as "gid", coalesce(name, 'apple') as "name" 
  from test 
  order by ("gid", "name") desc
  </code></pre>
  
  <p>And I want the above code to achieve the same result as this:</p>
  
  <pre><code>select id as "gid", coalesce(name, 'apple') as "name" 
  from test 
  order by (id, name) desc;
  </code></pre>
  
  <p>And it will work fine with:</p>
  
  <pre><code>select id as "gid", coalesce(name, 'apple') as "name" 
  from test 
  order by "gid" desc, "name" desc
  </code></pre>
  
  <p>So why can't Postgres find "gid"? And is <code>order by (a, b)</code> the same as <code>order by a,b</code>?</p>
  
  <p>Here is my create sql:</p>
  
  <pre><code>CREATE TABLE test ( "id" serial NOT NULL, "name" text NOT NULL, PRIMARY KEY ("id") );
  INSERT INTO test (name) VALUES ('Apple');
  INSERT INTO test (name) VALUES ('Orange'); 
  INSERT INTO test (name) VALUES ('Pear');
  </code></pre>