title: How to do LEFT JOIN with more than 2 tables?
body: <p>Currently I am doing this query:</p>
  
  <pre><code>select a.x, b.x, c.x
  from number as a, customer as b, numbergroup as c
  where a.b = b.b and a.c = c.c and c.b = b.b
  </code></pre>
  
  <p>However, I want to retrieve records from table "a" even if "a.c = null", which is not retrieved due to the join between "a" and "c".</p>
  
  <p>I have found information about <a href="http://www.w3schools.com/sql/sql_join_left.asp" rel="noreferrer"><code>left join</code></a> but I don't know how to do it when the query involves more than two tables like in this case.</p>