change.php

<?php
include_once('class.db.php');
$db = new db;
$error = Array();

try{
    // is there a variable for full name
    if(empty($_GET['fullName'])){
        $error[] = 'Full Name Not Provided.';
        throw new Exception(implode(' ',$error));
    }
    // find a comma
    $comma = strpos($_GET['fullName'],',');

    // if comma, strip it out and put first and last name into an array
    if($comma > 0) {
        $fullName = explode(',',str_replace(' ','',$_GET['fullName']));
        $fullName = array_reverse($fullName);
    }else{
        $fullName = explode(' ',$_GET['fullName']);
    }

    // check for first name
    if(empty($fullName[0])){
        $error[] = 'First Name not Provided.';
    }

    // check for last name
    if(empty($fullName[1])){
        $error[] = 'Last Name not Provided.';
    }

    // count the number of errors and throw an exception
    if(count($error) > 0) {
        throw new Exception(implode(' ',$error));
    }

    //Determine if Person already exists in database
    $sql = "SELECT * FROM whosHere WHERE firstname = '".ucfirst($fullName[0])."' AND lastname = '".ucfirst($fullName[1])."'";
    $result = $db->conn->query($sql);

    if($result->num_rows > 0){
        $row = $result->fetch_object();
        $status .= ($row->present==1) ? "out":"in";

        $sql = "UPDATE whosHere SET time=now(), present=";
        $sql .= ($row->present==1) ? 0:1;
        $sql .= " WHERE firstname = '".ucfirst($fullName[0])."' AND lastname = '".ucfirst($fullName[1])."'";

        $result = $db->conn->query($sql);

        echo json_encode(Array('opt'=>$status, 'result'=>true));
    }else{
        $sql = "INSERT INTO whosHere (firstname, lastname, time, present) VALUES ('".ucfirst($fullName[0])."', '".ucfirst($fullName[1])."',now(),1)";
        $sql = $db->conn->query($sql);

        echo json_encode(Array('opt'=>'in', 'result'=>true));

    }
}catch (Exception $e){
    echo json_encode(Array('message'=>$e->getMessage(),'result'=>false));
}