title: Database: Can I have nullable attributes in a third normal form database?
body: <p>I have a nullable <code>winnerID</code> attribute which is constantly updated according to the bidding of an auction.</p>
  
  <p>This attribute is set to save sometime in the end to calculate who won the auction. But this value is null initially.</p>
  
  <p>Will this violate Third Normal Form? I knew Rule 4 of 1NF states that I cannot have nullable attribute, but the note says this is a controversial statement.</p>
  
  <p>May you please clarify this for me? Thank you!</p>