title: mysql calculate multiplication with group by
body: <p>Please how to calculate multiplication with group by.</p>
  
  <p>For example </p>
  
  <p>table</p>
  
  <pre><code>id      value
  1       1
  1       2
  2       1
  2       2
  2       3
  3       0
  3       3
  </code></pre>
  
  <p>I want next result using group by.</p>
  
  <pre><code>id      value
  1       2
  2       6
  3       0
  </code></pre>
  
  <p>Thanks too much in advance.</p>