BuddyPress.org

I have created a phone number as Buddypress Profile field. I need to check that no two or more user accounts share the same phone number. My query below is not enforcing the restriction.

I need help to resolve this.

function bp_phone_number_validate() {
   global $bp;
   global $wpdb;

  // check if phone number is in use
  $result=$bp->get_var("SELECT COUNT(*) FROM {$bp->profile->wp_bp_xprofile_data} WHERE value = '{$_POST['field_2']}' GROUP BY id;");

  if($result > 0){
    $bp->signup->errors['field_2'] = __( 'Phone number is already in use.', 'buddypress' );
  }   
}
add_action( 'bp_signup_validate', 'bp_phone_number_validate');