title: Oracle query to resolve column values concatenation
body: <p>I have three columns in a tables</p>
  
  <pre><code>Column names with datatypes
  First_week - Number 
  Days       - Number
  Second_week- Number
  
  Column Values
  8
  6
  11
  </code></pre>
  
  <p>I want to concatenate these values such that result returns  8/6/11
  If anyone of the column values are null then the concatenation must be 8/-/11
  If all are null then the result must be -/-/-
  How can this be achieved in an oracle query?</p>