title: sum last 7 days of sales in new column
body: <p>I have the following data set: </p>
  
  <p><img src="https://i.stack.imgur.com/lsBlF.png" alt="enter image description here"></p>
  
  <p>I want to create a new column that sums the last 7 days of sales. So the query result should look be the following: </p>
  
  <p><img src="https://i.stack.imgur.com/DQwGI.png" alt="enter image description here"></p>
  
  <p>Pls help
  Thanks!</p>