title: SQL not displaying null values on a not equals query?
body: <p>This is just a question out of curiosity but I am looking at a database and pulling data from a table with a query on one of the columns.  The column has four possible values <code>null</code>, <code>0</code>, <code>1</code>, <code>2</code>.  When I run the query as:</p>
  
  <pre><code>SELECT * FROM STATUS WHERE STATE != '1' AND STATE != '2';
  </code></pre>
  
  <p>I get the same results as running:</p>
  
  <pre><code>SELECT * FROM STATUS WHERE STATE = '0';
  </code></pre>
  
  <p>I.e. rows with a null value in the top command in the queried column seem to be omitted from the results, does this always happen in SQL?</p>
  
  <p>I'm running my commands through Oracle SQL Developer.</p>