Untitled

<?php
session_start();
function DBConnection(){

    $host='localhost';
    $dbname='tic_tac_toe';
    $user='root';
    $pass='';

    try {
      $DBH = new PDO("mysql:host=$host;dbname=$dbname", $user, $pass);
      $DBH->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );
        return $DBH;
    }
    catch(PDOException $e) {
        echo 'ERROR: ' . $e->getMessage();
    }

}//function ends
function sqlexec($sql, $vars, $conn, $placeholder){
    try {
        $stmt = $conn->prepare($sql);
        for ($i=0; $i < count($vars); $i++) {
            $stmt->bindParam($placeholder[$i], $vars[$i]);
        }
        $result = $stmt->execute();
        return $stmt;
    } catch (Exception $e) {
        echo 'Error: '.$e->getMessage();
    }
}
$conn = DBConnection();
$sql = "SELECT * FROM games WHERE gamer2=''";
$stmt = sqlexec($sql,array(),$conn,array());
if ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
    $sql = "UPDATE games
    SET gamer2 = :gamer2
    WHERE id=:id";
    $gamer2 = "guest".rand();
    $_SESSION['id'] = $row['id'];
    $gamer1 = "guest";
    $stmt = sqlexec($sql,array($gamer2,$_SESSION['id']),$conn,array(':gamer2',':id'));
    $_SESSION['player'] = $gamer2;
}else {
    $sql = "INSERT INTO games (gamer1,gamer2)
    VALUES (:gamer1,:gamer2)";
    $gamer1 = "guest".rand();
    $gamer2 = "";
    $stmt = sqlexec($sql,array($gamer1,$gamer2),$conn,array(':gamer1',':gamer2'));
    $_SESSION['id'] = $conn->lastInsertId();
    $turn = 'x';
}
?>
<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title>tic tac toe</title>
        <link rel="stylesheet" href="style.css">
        <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
        <script type="text/javascript">
            <?php if(isset($turn)){echo "var xo='x';
                var turn = 0;";}
            else{echo "var xo='o';
                var turn = 0;";} ?>
            <?php echo "var id=".$_SESSION['id'].""; ?>
        </script>
        <meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
    </head>
    <body>
        <?php echo $gamer1.' vs '.$gamer2; ?>

    <div class="table-responsive vcenter">
        <table>
            <tr>
                <td class="td" id="td1" onclick="tdclk(this)"></td>
                <td class="td" id="td2" onclick="tdclk(this)"></td>
                <td class="td" id="td3" onclick="tdclk(this)"></td>
            </tr>
            <tr>
                <td class="td" id="td4" onclick="tdclk(this)"></td>
                <td class="td" id="td5" onclick="tdclk(this)"></td>
                <td class="td" id="td6" onclick="tdclk(this)"></td>
            </tr>
            <tr>
                <td class="td" id="td7" onclick="tdclk(this)"></td>
                <td class="td" id="td8" onclick="tdclk(this)"></td>
                <td class="td" id="td9" onclick="tdclk(this)"></td>
            </tr>
        </table>
    </div>
        <script type="text/javascript" src="script.js"></script>
    </body>
</html>