title: Why does this SQL code give error 1066 (Not unique table/alias: 'user')?
body: <p>This is my table structure:</p>
  
  <p><a href="https://i.stack.imgur.com/uGZUV.jpg" rel="noreferrer"><img src="https://i.stack.imgur.com/uGZUV.jpg" alt="alt text"></a>
  </p>
  
  <p>The error message is:</p>
  
  <blockquote>
    <p>#1066 - Not unique table/alias: 'user'</p>
  </blockquote>
  
  <p>The following is my code. </p>
  
  <pre><code>SELECT article.* , section.title, category.title, user.name, user.name
  FROM article
  INNER JOIN section ON article.section_id = section.id
  INNER JOIN category ON article.category_id = category.id
  INNER JOIN user ON article.author_id = user.id
  LEFT JOIN user ON article.modified_by = user.id
  WHERE article.id = '1'
  </code></pre>