title: Oracle "(+)" Operator
body: <p>I am checking some old SQL Statements for the purpose of documenting them and probably enhancing them.</p>
  
  <p>The DBMS is Oracle</p>
  
  <p>I did not understand a statement which read like this:</p>
  
  <pre><code>select ...
  from a,b
  where a.id=b.id(+)
  </code></pre>
  
  <p>I am confused about the <code>(+)</code> operator, and could not get it at any forums... (searching for + within quotes didn't work either).</p>
  
  <p>Anyway, I used 'Explain Plan' of SQLDeveloper and I got an output saying that <code>HASH JOIN, RIGHT OUTER</code>, etc.</p>
  
  <p>Would there be any difference if I remove the <code>(+)</code> operator at the end of the query? Does the database have to satisfy some condition (like having some indexes, etc.) before <code>(+)</code> can be used?? It would be greatly helpful if you can provide me a simple understanding, or some good links where I can read about this.</p>
  
  <p>Thanks!</p>