function getQuizes($quizNo)
{
    if($quizNo==NULL)
    {
        $quizNo=0;
    }
    require('database.php');
    $sql = "SELECT * FROM quiz LIMIT ".$quizNo.",1";
    $result = $conn->query($sql);
    while($row=$result->fetch_assoc())
    {
        echo $row['question'];
    }
    $quizNo++;
    $sql = "SELECT * FROM quiz";
    $result = $conn->query($sql);
    $rowcount=mysqli_num_rows($result);

    if($quizNo>=$rowcount)
    {
        $quizNo=0;
    }
    return $quizNo;
}

function getQuizes_answer1($quizNo)
{
    include_once('database.php');
    if($quizNo!=0)
    {
        $quizNo--;
    }
    $sql = "SELECT * FROM quiz LIMIT ".$quizNo.",1";
    $result = $conn->query($sql);
    while($row=$result->fetch_assoc())
    {
        echo $row['answer1'];
    }
    $sql = "SELECT * FROM quiz";
    $result = $conn->query($sql);
    $rowcount=mysqli_num_rows($result);
    if($quizNo>=$rowcount)
    {
        $quizNo=0;
    }
$conn->close();
}

<?php
    $i = isset($_SESSION['next']) ? $_SESSION['next'] : NULL;
    if(isset($_POST['next']))
    {
        $i = getQuizes($i);
        $_SESSION['next'] = $i;
 ?>
 <div class="answers_block">
     <table>
                <tr>
                    <td><?php getQuizes_answer1($i);?></td>
                </tr>
     </table>
 </div>
     <?php
     }
     ?>
       <form method="post" action="<?php echo $_SERVER['PHP_SELF']; ?>">
           <input name="next" value="Next" type="submit" />
       </form>

<?php
$servername = "localhost";
$username = "root";
$password = "";
$database="quiz_db";
// Create connection
$conn = new mysqli($servername, $username, $password, $database);
// Check connection
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}