title: SQL DatePart Week, year to reflect fiscal year
body: <p>I currently have a report that uses DATEPART to return the week a 'car' was returned. However, the business I work for fiscal year starts first Sunday of the year (this instance commencing 03/01/2016 would be week 1). However, using SQL 'DATEPART wk'  would return this date is week 2:</p>
  
  <p><strong>Current outcome using DATEPART (wk, year etc):</strong></p>
  
  <pre><code>CarTitle      ReturnDate      Year       Week       
  Car 1         30/12/2015      2015        53
  Car 2         02/01/2016      2016        1
  Car 3         03/01/2016      2016        2
  Car 4         05/01/2016      2016        2
  Car 5         10/01/2016      2016        3
  Car 6         17/01/2016      2016        4
  </code></pre>
  
  <p><strong>Example of expected outcome:</strong></p>
  
  <pre><code>CarTitle      ReturnDate      Year       Week       
  Car 1         30/12/2015      2015        53
  Car 2         02/01/2016      2015        53
  Car 3         03/01/2016      2016        1
  Car 4         05/01/2016      2016        1
  Car 5         10/01/2016      2016        2
  Car 6         17/01/2016      2016        3
  </code></pre>