Help with a complex mysql command executed on php

Hi, i am trying to connect two tables and run a function along side
the two tables are users and buddies
i am using a custom php getage function to determine age which is used in the mysql command too
the getage function is

function getage($strdate)
{
    $dob = explode("-",$strdate);
    if(count($dob)!=3)
    {
      return 0;
    }
    $y = $dob[0];
    $m = $dob[1];
    $d = $dob[2];
    if(strlen($y)!=4)
    {
      return 0;
    }
    if(strlen($m)!=2)
    {
      return 0;
    }
    if(strlen($d)!=2)
    {
      return 0;
    }
  $y += 0;
  $m += 0;
  $d += 0;
  if($y==0) return 0;
  $rage = date("Y") - $y;
  if(date("m")<$m)
  {
    $rage-=1;
    
  }else{
    if((date("m")==$m)&&(date("d")<$d))
    {
      $rage-=1;
    }
  }
  return $rage;
}

Code (markup):

the two tables to be used with the necessary fields are users(id,name,birthday) buddies(uid,tid). The sql which i have come up with is

$sql = "SELECT
          a.id,a.name,a.birthday, b.uid, b.tid FROM users a
          INNER JOIN buddies b ON a.id = $who AND a.id = b.uid OR a.id = b.tid
          AND month(`birthday`) = month(curdate()) AND dayofmonth(`birthday`) = dayofmonth(curdate())
          GROUP BY 1,2 ORDER BY a.name ASC 
          LIMIT 0, 10
    ";

Code (markup):

$who variable is the id of the person and i wish to check if any of his buddies has a birthday on the current day. for which i need to tally the id of users with uid or tid of buddies. Can anybody please direct me in correcting this code ?? The function isnt a problem, the sql is a problem . Please help...