title: Row to column transform
body: <p>After multiple join, I have raw results.</p>
  
  <pre><code>+----------------------------------------------------------------------+
  | Results                                                              |
  +----+----------+-------------+----------+-----------+-----------------+
  | id | group_id | question_id | question | answer_id | answer | input  |
  +----+----------+-------------+----------+-----------+-----------------+
  | 1  | 10001    | 1           | How old  | 1         | 25     | NULL   |  
  | 2  | 10001    | 2           | What like| 3         | Cola   | NULL   |
  | 3  | 10001    | 2           | What like| 4         | Other  | HotDog |
  | 4  | 10001    | 3           | City     | 5         | NYC    | NULL   |
  | 5  | 10001    | 4           | Name     | 7         | Other  | Alex   |
  | 6  | 10002    | 1           | How old  | 1         | 25     | NULL   | 
  | 7  | 10002    | 2           | What like| 6         | Candy  | NULL   |
  | 8  | 10002    | 3           | City     | 8         | LA     | NULL   | 
  | 9  | 10002    | 4           | Name     | 7         | Other  | Roman  | 
  +----+----------+-------------+----------+-----------+--------+--------+
  </code></pre>
  
  <p>But now I want to see it in "one row view" by group_id.
  Such as:</p>
  
  <pre><code>+----+----------+-------------+----------+-----------+
  | id | How Old  |  What like  | City     |  Name     |
  +----+----------+-------------+----------+-----------+
  | 1  | 25       | Cola,HotDog | NYC      | Alex      |
  | 2  | 25       | Candy       | LA       | Roman     |  
  +----+----------+-------------+----------+-----------+
  </code></pre>
  
  <p>I don`t know normal group_by/concat construction for that. What  must I do?</p>