title: Partial Functional Dependency , still in 3NF?
body: <p>Relation schema R (ABCD)<br>
  Functional Dependencies are :<br>
       AB -> D<br>
       CB -> D<br>
       A->   C<br>
       C ->  A<br>
  Highest Normal Form ???  </p>
  
  <p>My understanding :  </p>
  
  <p>Candidate key = <strong>AB</strong> and <strong>BC</strong>   </p>
  
  <p>While creating table both AB and BC can not consider as Primary key. So let's take one by one.   </p>
  
  <p><strong>For Key AB :</strong><br>
  <code>AB -&gt; D  ( Fully Functional Dependency , so no problem )</code><br>
  <code>CB -&gt; D ( ??? )</code><br>
  <code>A  -&gt; C (partial Functional Dependency , as left side contains only part of key)</code><br>
  <code>C  -&gt; A ( Functional Dependency , So no problem )</code>  </p>
  
  <p><strong>For Key BC</strong>   </p>
  
  <pre><code>AB -&gt; D ( ???? )  
  CB -&gt; D ( Fully Functional Dependency , so no problem )  
  A  -&gt; C  (Functional Dependency )  
  C  -&gt; A  ( Partial Functional Dependency , as it's LHS is part of Key )   
  </code></pre>
  
  <p>Now through both key's ,  relation contains <strong>Partial Functional Dependency.</strong><br>
  Then it should not be in 2NF.<br>
  But answer is 3NF.<br>
  Please correct me. </p>