title: SQL Query - How to remove null and replace with blank
body: <p>Here is my query:</p>
  
  <pre><code>SELECT ename, sal, comm
  FROM EMP
  WHERE comm IS NULL
  ORDER BY sal DESC;
  </code></pre>
  
  <p>I would like to replace the <code>NULL</code> result in the <code>comm</code> column with a blank space. I have been told to under <code>SELECT, write NULL(comm,' ')</code>, however this comes up with an error, saying invalid number. The query works if I have <code>NULL(comm, 0)</code>, returning with 0 in the column.</p>
  
  <p>From my understanding this means I can only have a number value in this column, however I want the blank space. Is someone able to please give me some guidance?</p>