title: Difference between today and 7 days ago
body: <p>I spent some hours googling now but I can't find a solution that fits, so you guys are my last hope.</p>
  
  <p>I have sales data that is not aggregated (every single item sold listed seperately). I aggregate them in Tableau by Date so I can see on what day we sold which amount if items. What I'm trying to do now is compare the value of today (Saturday) with the value of last Saturday. My problem is that I dont know how to aggregate the sales of 7 days ago and today in the same table so I can compare them.</p>
  
  <p>Is there a proper way in tableau to do this? Really grateful for every answer.</p>