title: Power Query Table.FillDown with condition
body: <p>Is there a way to fill down a table based on a condition?</p>
  
  <p>A sample of my table below. I want to filldown the Date column based on the Contract column. For example, if the contract does not starts with GB, then filldown the Date of the previous row, otherwise leave blank.</p>
  
  <pre><code> Contract    Date     Role
  01F001     3/7/2016     A
  01F017     5/6/2016     A
  GB0007                  B
  GB0007                  B
  LBCA09     2/29/2016    A
  LBCA09                  B
  LBCA09                  B
  LBCA09                  B
  LBCA12     2/25/2016    A
  LBCA12                  B
  </code></pre>
  
  <p>Here is the final data I want</p>
  
  <pre><code>Contract    Date    Role
  01F001  3/7/2016    A
  01F017  5/6/2016    A
  GB0007              B
  GB0007              B
  LBCA09  2/29/2016   A
  LBCA09  2/29/2016   B
  LBCA09  2/29/2016   B
  LBCA09  2/29/2016   B
  LBCA12  2/25/2016   A
  LBCA12  2/25/2016   B
  </code></pre>
  
  <p>I tried to add a if statement outside of the Table.Filldown function but got an syntax error. </p>
  
  <pre><code>= if not Text.StartsWith([Contract],"GB") then Table.FillDown(#"Replaced Value",{"Date"})
  </code></pre>
  
  <p>Any help is appreciated!</p>