title: Compare Monday's data to previous Mondays in SQL Server
body: <p>I am trying to figure out how to compare the current day's data to the same data from a week ago, 2 weeks, etc.  Let's say I have a table called "Order" with 2 columns:</p>
  
  <pre><code>Order table
  -----------
  OrderID int identity
  OrderDate datetime
  </code></pre>
  
  <p>If today, is Monday, I would like to be able to compare the number of orders from today to the previous Mondays for an entire year.  Is this possible with a single SQL Server query?  I'm using SQL 2008 if it makes a difference.</p>