title: Pivot table returns multiple rows with NULL, results should be grouped on one row
body: <p>I have the table below which I am looking to pivot so that the descriptions in column 1 become column headers in the new pivot. </p>
  
  <pre><code> Nominal Group  | GrpID | Description     | Value       | CustomerID
   ---------------+-------+-----------------+-------------+-----------
   Balance Sheet  | 7     | BS description  | 56973.10    |     2
   Cost of Sales  | 4     | COS description | 55950.17    |     2
   Sales          | 1     | Sales           | -178796.18  |     2
   Labour Costs   | 5     | Wages           | 18596.43    |     2
   Overheads      | 6     | Rent            | 47276.48    |     2
  </code></pre>
  
  <p>I'm using the code below to get the result set below that:</p>
  
  <pre><code>select * from trialbalancegrouping 
  PIVOT (Sum(value)
  for nominalgroupname in ([Sales],[Cost of Sales],[Labour Costs],[Overheads])) AS PVTtable
  </code></pre>
  
  <p>-</p>
  
  <pre><code> GrpID |  Description  | CustomerID |    Sales   | Cost of Sales | Labour Costs | Overheads
   ------+---------------+------------+------------+---------------+--------------+-----------
      1  |    Sales      |      2     | -178796.18 |     NULL      |      NULL    |     NULL
      2  |COS Description|      2     |    NULL    |   55950.17    |      NULL    |     NULL
      3  |    Labour     |      2     |    NULL    |     NULL      |   18596.43   |     NULL
      4  |   Overheads   |      2     |    NULL    |     NULL      |      NULL    |   47276.48
  </code></pre>
  
  <p>Ideally, I'd want the output to be one row per customer, like this:</p>
  
  <pre><code>CustomerID |    Sales   |  Cost of Sales | Labour Costs | Overheads
  -----------+------------+----------------+--------------+------------
       2     | -178796.18 |     55950.17   |   18596.43   |   47276.48
  </code></pre>