title: SQL query, only select if column is not null else don't select
body: <p>This is what i am trying to do</p>
  
  <pre><code> SELECT `a`, `b`, `c` FROM `tbl` WHERE `a` IS NOT NULL OR `b` IS NOT NULL OR `c` IS NOT NULL WHERE id = ?
  </code></pre>
  
  <p>If a and c are null and b isn't I still receive this result set\</p>
  
  <pre><code> a      b     c 
  ____   ____   ____   
  
  NULL  value   NULL
  </code></pre>
  
  <p>But i only want that it returns this</p>
  
  <pre><code>   b
    ____
  
    value
  </code></pre>
  
  <p>Thanks in advance! </p>