title: (Quicksight) How to Sum Values only from Unique Fields
body: <p>My data set has a {Invoice No} field that I want to sum the cost of. All invoice numbers are unique and have <em>one</em> cost value. However, because there are multiple {Part No} fields in each {Invoice No}, Quicksight multiplies this one cost by however many part numbers there are in each invoice, so the sum ends up being some multiple of the real value that I want. This is what the table view looks like:</p>
  
  <pre><code>{Invoice No}    {Part No}     {cost}
  12345            001           10.12
  12345            002           10.12
  12345            003           10.12
  </code></pre>
  
  <p>How can I just use the first {cost} value of each {Invoice No}, so it doesn't duplicate it? I thought a workaround could be creating a new field that omits any duplicate invoice numbers, but don't know how to do that in Quicksight.
  Any solution would be much appreciated.</p>