title: Group DataTable by some columns and remove repeated values?
body: <p>I have a DataTable in my Winforms application that contains data like this:</p>
  
  <pre><code>| ItemName | ItemNo |   ItemValue
       B         1            1,4
       B         1            1,9
       B         1            2,2
       A         2            2,0
       A         2            2,7
       A         2            3,1
       C         3            1,3
       C         3            1,5
       C         3            2,1
  </code></pre>
  
  <p>How can i make my DataTable to show in a DataGridView values like this?:</p>
  
  <pre><code>| ItemName | ItemNo |   ItemValue
       B         1            1,4
                              1,9
                              2,2
       A         2            2,0
                              2,7
                              3,1
       C         3            1,3
                              1,5
                              2,1
  </code></pre>
  
  <p>Like grouping and removing the repeated values from the datatable and inserting empty values maybe? </p>