title: Select only Columns without Null values in Oracle
body: <p>I have 20 columns in my table....</p>
  
  <p>How can I select only columns that don't have null value</p>
  
  <pre><code>col1 col2 col3
  20    12   null
  </code></pre>
  
  <p>Desired output</p>
  
  <pre><code>col1 col2 
  20    12  
  </code></pre>