title: Datepart Week Sql (With 53 weeks for year)
body: <p>I'm calculating the week for a specific date in SQL for example 
  '2016-01-20' (<code>yyyy-mm-dd</code>) but SQL returns week: 4, and that is wrong because this year the first week started on '2016-01-04' the result must be week: 3.</p>
  
  <p>I think the issue is generatad because 2015 was a year with 53 weeks, any solution to that? Thank you and I'm sorry for my bad English</p>