根据条件保留所有以前的数据 - Keep all previous data according to condition

我正在尝试根据计数器显示两个产品名称。我已经声明了一个会话变量"计数器"。如果单击按钮，我想显示第一个产品名称，如果再次单击按钮，我想显示两个产品名称。

山谷

苹果电脑

但是，如果我第二次单击该按钮，则第二个产品名称将替换第一个产品名称;我希望两个产品都显示。

我将如何解决这个问题？

我的代码：

<?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 }
?>

当您提出第二个请求时，您将失去当前状态;您不再有权访问第一个产品名称。解决此问题的一种方法是添加第二个会话变量来跟踪产品，如下所示：

<?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 }
?>

要记住的一点：mysql_* 函数的使用已被弃用，坦率地说，在新开发中使用很危险。您不能将预准备语句与这些函数一起使用，这意味着任何人都可以严重弄乱您的数据库。在此处阅读更多相关信息。

只需更改if块

即可像这样

if($_SESSION['counter']==1 || $_SESSION['counter']==2) {
  echo $data3['name']."<br>";
}

这样，第一个产品将以两种状态显示

更新

我会这样做，不要在会话中存储计数器值，将产品 ID 存储为 array，然后您可以使用count()来获取会话中的产品数量

这样，您就可以像这样查询数据库中存储的 ID

$query3 = "select * from product where id IN (1,2);

只需在页面上列出即可

注意：不要使用mysql_* API，它已弃用 PDO 它的安全并支持许多数据库;