title: sql coalesce not working with group by mysql
body: <p>I have a table like:</p>
  
  <pre>
  +----+------+-------+
  | id | name | value |
  +----+------+-------+
  |  1 | bob  | k     |
  |  2 | kate | NULL  |
  |  3 | bob  | NULL  |
  |  4 | kate | w     |
  +----+------+-------+
  </pre>
  
  <p>And I want the following output:</p>
  
  <pre>
  +----+------+-------+
  | id | name | value |
  +----+------+-------+
  |  1 | bob  | k     |
  |  2 | kate | W     |
  +----+------+-------+
  </pre>
  
  <p>when  use coalesce like:</p>
  
  <pre><code>select id,name,coalesce(value) from hey group by name;
  
  </code></pre>
  
  <p>the output is:</p>
  
  <pre>
  +----+------+-------+
  | id | name | value |
  +----+------+-------+
  |  1 | bob  | k     |
  |  2 | kate | NULL  |
  +----+------+-------+
  
  
  </pre>
  
  <p>How can I achieve the desired output? please</p>