title: Convert column values to grouped comma-separated string
body: <p>I am using SQL Server 2008. I have a table like below:</p>
  
  <pre><code>ID  Name 
  1   a
  1   b
  2   c
  3   d
  </code></pre>
  
  <p>I want output like below:</p>
  
  <pre><code>ID  Name
  1   a,b
  2   c
  3   d
  </code></pre>