title: Alias a table in Knex
body: <p>I have a SQL query that refers to the same table twice, and I need to alias the table to two separate aliases. I can't quite figure out how to compose this with Knex.</p>
  
  <p>There's a 'Words' table and a 'Users' table. The Words table has two foreign keys, 'author_id' and 'winner_id', referencing the Users table's 'id' column.</p>
  
  <p>Here's the SQL I'm trying to compose in Knex:</p>
  
  <pre><code>SELECT w.*, ua.name, uw.name FROM Words AS w
  INNER JOIN Users AS ua ON w.author_id = ua.id 
  LEFT JOIN Users AS uw ON w.winner_id = uw.id
  </code></pre>
  
  <p>I'm a little lost as to how to do this in Knex. My first attempt didn't involve aliasing, and so I got a 'table used more than once' error. When I tried to use the .as() method, knex complained that there was a missing .from() clause. Is the .as() method only used for aliasing subqueries, and I shouldn't expect it to be used to alias tables?</p>