title: Get week number in year from date
body: <p>I am looking for a query which will return the week number from given date.</p>
  
  <p>What I've already tried is this:</p>
  
  <pre><code>select datepart(wk, '2017-02-01')
  </code></pre>
  
  <p>but this returns 5 instead of 6. (february 1st is the 6th week of the year).</p>
  
  <p>(week numbers with red)</p>
  
  <p><a href="https://i.stack.imgur.com/HptV2.png" rel="noreferrer"><img src="https://i.stack.imgur.com/HptV2.png" alt="enter image description here"></a></p>