Joining two tables, customers and orders to get list of all customers and the order number IF they have an order
<pre><code>    SELECT a.org, 
           a.id, 
           a.Name, 
           b.ordNum 
      FROM customers A, 
           orders B 
     WHERE a.org  = 'JJJ' 
       AND a.org  = b.org (+)
       AND b.addr_type (+) = 'ST' -- &lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt;&lt; why do i need to add (+) here
       AND a.cust_id = b.cust_id (+)
  ORDER BY 2
</code></pre>

<p>I have a table with a list of customers (A) and a table called orders (B) that have orders the customers may have placed .
The query i have above is supposed to give me the names of all customers and the order number IF there is an order linked to that customer.</p>

<p>My question is.. why do i need to add the (+) after b.addr_type to get all the customers even if they have not placed an order. </p>