title: Oracle (+) Operator with constant value
body: <p>Consider below Oracle query: </p>
  
  <pre><code>SELECT psn_id, nvl(psn_name_lang, psn_name_kurz) psn_name, cli_code, cli_id, cli_cmp_id, p2.pat_value cli_domain
  FROM tabl_psn_obj, table_cli, table_pat p1, table_pat p2
  WHERE psn_id = p1.pat_psn_id
    AND p1.pat_value = to_char(cli_cmp_id)
    AND p1.pat_att_id = 3
    AND p2.pat_att_id(+) = 48 &lt;---- what does this mean
    AND p2.pat_psn_id = psn_id
    AND p2.pat_value = i_domain
    AND cli_cmp_id = i_cmp_id;
  </code></pre>
  
  <p>I'm a lit bit confused about his <code>(+)</code> operator. As I know the <code>(+)</code> is a shortcut for <code>OUTER JOIN</code>, depending on which side you put it on, it indicates a <code>LEFT</code> or <code>RIGHT OUTER JOIN</code>. </p>
  
  <p>But in the above query the left outer join is with some constant value, not with any other table ID. What does this mean? What is the similar thing in PostgreSQL?</p>
  
  <p>Maybe this question could be generalized but I don't understand the meaning with a constant value.</p>