title: How can I sum strings in one column into one row in Microsoft SQL? Group by does not work since it is MSSQL
body: <p>for example we have table with three columns</p>
  
  <pre><code>Column A |  Column B | Column C
  -------------------------------
  P1       |    10     |    A    
  P1       |    20     |    B
  P1       |    30     |    C
  P2       |    30     |    D
  P2       |    40     |    E
  </code></pre>
  
  <p>How do I have to write SELECT query in <strong>Microsoft SQL</strong> to have this kind of result</p>
  
  <pre><code>Column A |     Column B      |   Column C
  ------------------------------------------
  P1       |    10, 20, 30     |    A, B, C
  P2       |    30, 40         |    D, E
  </code></pre>