title: How to merge two rows in one if there is one same value in a column and change columns name
body: <p>I've this query</p>
  
  <pre><code>SELECT
      pm.post_id,
      pm.meta_key,
      pm.meta_value
  FROM 
     birr_postmeta as pm,
     birr_posts as p
  WHERE pm.meta_key IN ('ratings_average', 'ratings_users')
      AND pm.meta_value &lt;&gt; 0
      AND pm.post_id = p.ID
  ORDER BY pm.post_id ASC
  </code></pre>
  
  <p>that return me this:</p>
  
  <p><img src="https://i.imgur.com/Ikw3dzn.jpg" alt="image"></p>
  
  <p>What I want to obtain, from these table, is something like this</p>
  
  <pre><code>+--------+---------------+--------------+
  |post_id |  rating_users |rating_average|
  +--------+---------------+--------------+
  |    7   |       1       |      5       |
  |   35   |       3       |      4       |
  |   101  |       2       |     4.5      |
  |   127  |       2       |      4       |
  |   225  |       1       |      4       |
  +--------+---------------+------------+
  </code></pre>
  
  <p>How can I achieve this?</p>