title: MySql select showing total grouped by condition
body: <p>I have this table:</p>
  
  <pre><code>SALESMAN |   INVOICE     |   VALUE   
  1        |   7470        |   10       
  1        |   7471        |   20       
  1        |   7472        |   30     
  2        |   7473        |   40       
  2        |   7474        |   50       
  </code></pre>
  
  <p>I want a query in order to get this result:</p>
  
  <pre><code>SALESMAN |   INVOICE     |   VALUE   |  TOTAL_VALUE  | TOTAL_ITEMS
  1        |   7470        |   10      |  40           | 3
  1        |   7471        |   20      |  40           | 3
  1        |   7472        |   10      |  40           | 3
  2        |   7473        |   40      |  90           | 2
  2        |   7474        |   50      |  90           | 2
  </code></pre>
  
  <p><code>TOTAL_VALUE</code> is the sum of all <code>VALUE</code> for the same <code>SALESMAN</code>. 
  <code>TOTAL_ITEMS</code> is the amount of rows with the same <code>SALESMAN</code>.</p>
  
  <p>Is possible to achieve this in MySql?</p>