title: How to get the first day of the week, depending on NLS
body: <p>I want to get the date of the first day of the week but I want it to be dependant to NLS parameters. Say , when I run it on America it should give me Sundays date, but in Turkey it should give me Monday..</p>
  
  <pre><code>select trunc(to_date(sysdate,'dd-mm-yy'),'iw')from dual;
  </code></pre>
  
  <p>How can I make it dependant?</p>