title: Oracle SQL recursive query to find parent of level one
body: <p>suppose i have a table service :</p>
  
  <pre><code>     Name      | ID | PARENT_ID | LEVEL | 
  ------------------------------------------- 
   s1            | 1  | null      | 0     | 
   s2            | 2  | 1         | 1     | 
   s3            | 3  | 1         | 2     |      
   s4            | 4  | 2         | 2     | 
   s5            | 5  | 3         | 3     | 
   s6            | 6  | 4         | 3     |
  </code></pre>
  
  <p>and i want to get the parent of level 1 for s6(id=6) which should return s2 , is there a way to make a recursive query until a level is reached ?</p>