title: Join table only if record exists or return null?
body: <p>I am querying records from multiple tables. Records exist for any <code>id_value</code> in <code>schema.table_one</code> but may or may not exist in <code>schema.table_two</code> (or additional tables joined in the query).</p>
  
  <p>The following query format works fine when there is a record with the given  <code>id_val</code> in all queried tables:</p>
  
  <pre><code>SELECT one.value_one, two.value_two
  FROM schema.table_one one LEFT JOIN schema.table_two two 
      ON one.id_value = two.id_value 
      WHERE one.id_value = 'id_val' AND two.other_column = 'other_val';
  </code></pre>
  
  <p>If the record is removed from <code>table_two</code> or doesn't exist (and/or any additionally joined tables) then no results are returned. </p>
  
  <p>Is there a way to either return null for <code>two.value_two</code> if there is no record for the given <code>id_val</code> in <code>table_two</code> or only join if the record exists? </p>