title: Creating a calculated field in Tableau using 3 columns
body: <pre><code>    Date1         Date2       Line Item    Total
  
      May10,2009    May9,2009       10        40
  
      May9,2009     May10,2009      20        10
  
      May9,2009     May8,2009       20        30
  
      May8,2009     May11,2009      30        0
  </code></pre>
  
  <p>This is my Table in Tableau. I want to create a calculated field for last column. If Date2 value has a match in Date1 Column, the new value is equal to the sum of all values corresponding to that that in Line Item column. Is this possible in tableau using calculation or in some way? example: 'May9,2009' in Date2 COLUMN has two occurrences in Date1 Column. hence the two values in Line Item column (20+20) is added and new calculated field shows 40.</p>
  
  <p>Someone please help. </p>