根据条件保留所有先前的数据

Question

I am trying to display two product names depending on a counter. I've declared a session variable 'counter'. I want to show the first product name if the button is clicked, and I want to show two product names if the button is clicked again.

Dell

Mac

However, if I click the button the second time, the second product name replaces the first product name; I want both products to display.

How would I fix this?

My code:

<?php
session_start();
include('connect.php');

// if counter is not set, set to zero
if (!isset($_SESSION['counter'])) {
    $_SESSION['counter'] = 0;
}

// if button is pressed, increment counter
if (isset($_POST['button'])) {
    ++$_SESSION['counter'];
    // Get data according to id 

    $userid2 = $_POST['id2'];
    $query3 = "select * from product where  id='" . $userid2 . "'";
    $result3 = mysql_query($query3) or die(mysql_error());
    $data3 = mysql_fetch_array($result3);

    if ($_SESSION['counter'] == 1) {
        echo $data3['name'] . "<br>";
    }

    if ($_SESSION['counter'] == 2) {
        echo $data3['name'];
    }
}

// reset counter
if (isset($_POST['reset'])) {
    $_SESSION['counter'] = 0;
}

$query2 = "select * from product ";
$result = mysql_query($query2) or die(mysql_error());

$data = mysql_fetch_array($result);

$sr = $data['sr'];
$name = $data['name'];
$price = $data['price'];
$qunt = $data['quantity'];

$total += $data['price'];

while ($data = mysql_fetch_array($result)) {
    ?>
    <form method="POST" action="">
        <table border="1">
            <tr>
                <?PHP
                echo "<tr><td>" . $data['id'] . "</td><td>" . $sr . "</td><td >" . $name . "</a></td><td>" . $price . "</td><td>" . $qunt . "</td> ";
                ?>
            <tr>
        </table>
        <input type="hidden" name="id2" value="<?php echo $data['id'] ?>"/>

        <input type="hidden" name="counter" value="<?php echo $_SESSION['counter']; ?>"/>
        <input type="submit" name="button" value="Counter"/>
        <input type="submit" name="reset" value="Reset"/>

        <br/><?php echo $_SESSION['counter']; ?>
    </form>
<?php }
?>

Answer 1

When you make your second request, you're losing your current state; you no longer have access to the first product name. One way to fix this is to add a second session variable to keep track of products, as such:

<?php
session_start();
include('connect.php');

// if counter is not set, set to zero
if (!isset($_SESSION['counter']) || !isset($_SESSION['products'])) {
    $_SESSION['counter'] = 0;
    // Create a new array in your session
    $_SESSION['products'] = array();
}

// if button is pressed, increment counter
if (isset($_POST['button'])) {
    ++$_SESSION['counter'];
    // Get data according to id

    $userid2 = $_POST['id2'];
    $query3 = "select * from product where  id='" . $userid2 . "'";
    $result3 = mysql_query($query3) or die(mysql_error());
    $data3 = mysql_fetch_array($result3);

    // Add to your products session array
    $_SESSION['products'][] = $data3['name'];

    // Reduce to two products
    $_SESSION['products'] = array_slice($_SESSION['products'], -2, 2);

    // Print each product in your products array, max of two
    foreach($_SESSION['products'] as $name) {
        echo $name . "<br />";
    }
}

// reset counter
else if (isset($_POST['reset'])) {
    $_SESSION['counter'] = 0;
    $_SESSION['products'] = array();
}

$query2 = "select * from product ";
$result = mysql_query($query2) or die(mysql_error());

$data = mysql_fetch_array($result);

$sr = $data['sr'];
$name = $data['name'];
$price = $data['price'];
$qunt = $data['quantity'];

$total += $data['price'];

while ($data = mysql_fetch_array($result)) {
    ?>
    <form method="POST" action="">
        <table border="1">
            <tr>
                <?= "<tr><td>" . $data['id'] . "</td><td>" . $sr . "</td><td >" . $name . "</a></td><td>" . $price . "</td><td>" . $qunt . "</td> " ?>
            <tr>
        </table>
        <input type="hidden" name="id2" value="<?= $data['id'] ?>"/>

        <input type="hidden" name="counter" value="<?= $_SESSION['counter'] ?>"/>
        <input type="submit" name="button" value="Counter"/>
        <input type="submit" name="reset" value="Reset"/>

        <br/><?= $_SESSION['counter']; ?>
    </form>
<?php }
?>

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Something to keep in mind: the use of mysql_* functions is deprecated, and frankly, dangerous to use in new development. You can't use prepared statements with those functions, which means that anyone can seriously mess with your database. Read more about it here.