title: how to represent symmetric many to many relationship
body: <p>suppose i have a entity called USER and a relationship FRIENDSHIP exist between two USERs
  SO for that i have a table 'USER' and a relationship table 'FRIENDSHIP'</p>
  
  <p><Pre>   </p>
  
  <p>USER
  id  firstName  LastName
  1    taher     chhabrawala
  2    john      Dsouza
  3    rahul     singh
  4    deepak    patel</p>
  
  <p>Friendship
  id    id
  1     2
  1     3
  1     4
  4     1
  4     3</p>
  
  <p></Pre></p>
  
  <p>In the above table i am storing the same information twice i.e "taher is a friend of deepak and deepak is a friend of taher"</p>
  
  <p>Is there any way to reduce this redundancy ?</p>