title: How to use GROUP_CONCAT in a CONCAT in MySQL
body: <p>If I have a table with the following data in MySQL:</p>
  
  <pre><code>id       Name       Value
  1          A          4
  1          A          5
  1          B          8
  2          C          9
  </code></pre>
  
  <p>how do I get it into the following format?</p>
  
  <pre><code>id         Column
  1          A:4,5,B:8
  2          C:9
  </code></pre>
  
  <p><br>
  I think I have to use <code>GROUP_CONCAT</code>. But I'm not sure how it works.</p>