title: Left join using IS NULL does not work in DB2?
body: <p>I am trying to left join to tables using a query like this</p>
  
  <pre><code>SELECT * FROM table1 a, table2 b WHERE (a.ID = b.ID OR b.ID IS NULL) 
  </code></pre>
  
  <p>In Oracle, this is equivalent to a <code>LEFT JOIN</code> (and in other databases as well, afaik).</p>
  
  <p>Doing the same thing in DB2 (z/OS) produces an inner join - the <code>b.ID IS NULL</code> clause has no effect on the result, removing it does not change anything.</p>
  
  <p>Is there a way to make this work in DB2? Is this something that should work according to ANSI SQL?</p>
  
  <p>PS: I am aware that I can use the <code>JOIN</code> syntax, I'm just interested in why this doesn't work and if there is a way around this.</p>