Generating Family tree for multi level network

A database with members table with fields: member_id, referrer_id, level
Each time a member is registered, the level of the member referrer is increase by 1.
The highest level is 7.
How do I generate a family tree using table members when I choose a particular member.

 

If you want to build a straight-forward tree structure, I don't see how the member level will help you.
In any case, you need to use recursivity for this.
I do not know your code but in pseudo-code I would do this:

function getMemberData($id, $level = 0)
{
  // SQL to retrieve the data for this user
  $sql = "SELECT * FROM users WHERE member_id = $id";
  //....
  echo str_pad($input, $level * 5, "-", STR_PAD_LEFT) . $member['name'] . "<br/>";
  if ($member['referrer_id'] > 0)
    getMemberData ($member['referrer_id'], $level + 1);
}

// Then just call the function for your user
getMemberData (1337); // where 1337 is the user id

Code (markup):

This code will show something like this:
user
_____referrer 1
__________referrer2

Hope that would put you on the right track

aXe