title: Difference between Completely Non Trivial Dependency and Non Trivial Dependency
body: <p>What is the difference between Non Trivial Functional Dependencies and Completely non trivial Dependencies?</p>
  
  <p>As per as my search i found a confusing difference between the two. I visited <a href="http://www.tutorialspoint.com/dbms/database_normalization.htm" rel="nofollow">http://www.tutorialspoint.com/dbms/database_normalization.htm</a></p>
  
  <p>According to this, 
  <strong>Non-trivial</strong>: If an FD X → Y holds where Y is not subset of X, then it is called non-trivial FD.</p>
  
  <p><strong>Completely non-trivial</strong>: If an FD X → Y holds where x intersect Y = Φ, is said to be completely non-trivial FD.</p>
  
  <p>Being Y not subset of X and X intersect Y = Φ. Don't they point towards the same.</p>
  
  <p>Example: X={1,2,3,4}, Y={5,6}
  here we see Y is not subset of X and also Y intersect X = Φ. </p>
  
  <p>Then, My question is what is the reason behind saying difference between non trivial dependency and Completely non Trivial Dependency? If there is any difference, then what is that exact one. Please suggest me. I googled it, but not found the satisfactory one.</p>