title: Tree structure in sql in Oracle.How to show tree,child nodes and parent nodes in SQL Oracle
body: <p>I would like to show a tree structure in SQL with child nodes and parent nodes.
  I have a table like:</p>
  
  <pre><code>Employee
  -------------
  ID (int)
  FirstName (varchar)
  LastName (varchar)
  ParentID (int)
  Job (varchar)
  </code></pre>
  
  <p>which represents an employee. <strong>ParentID</strong> represent the manager of the employee has. I would like to have this table only with this structure.</p>
  
  <ol>
  <li>I would like to show the whole tree structure.</li>
  <li>I would like to show only the children nodes</li>
  <li>I would like to show only the parent nodes</li>
  </ol>
  
  <p><a href="http://i.stack.imgur.com/mCqdM.png" rel="nofollow">SampleDataImage</a></p>