title: Column 'user_id' in field list is ambiguous
body: <p>I am attempting to get the user information of the user who left this review.</p>
  
  <p>With the following code:</p>
  
  <pre><code>SELECT username, image, user_id FROM table_users AS us
  JOIN table_reviews AS re
  ON re.user_id = us.user_id
  WHERE us.user_id = 1 AND
  re.review_id= 1
  </code></pre>
  
  <p>I get the error: </p>
  
  <blockquote>
    <p>Column 'user_id' in field list is ambiguous</p>
  </blockquote>
  
  <p>What does this mean?</p>