我尝试将文件制作为html文件，或者直接将 <link rel="stylesheet" type="text/css" href="mystyle.css"> 立即放入，但它不起作用。
我希望能够更改 pharagraph producten 字体大小。
这是我到目前为止的代码（关于最后一部分（））
<?php
include('DatabaseConnector.php');
$database = new DatabaseConnector("test", "root", "");
<link rel="stylesheet" type="text/css" href="mystyle.css">
$email = $database->selectValue("SELECT emailadres FROM klant WHERE naam = 'Bibiche' AND achternaam = 'Laarakkers'");
echo "Het emailadres van Bibiche Laarakkers is $email.";
$productInfo = $database->selectSingleRow("SELECT gewicht, prijs, calorieen FROM product WHERE naam = 'Sausage Muffin with Egg Whites'");
echo "<h2> Sausage Muffin with Egg Whites </h2>";
echo "<p>Gewicht: " . $productInfo['gewicht'] . "<br>";
echo "Prijs: " . $productInfo['prijs'] . "<br>";
echo "Aantal Calorieën: " . $productInfo['calorieen'] . "</p>";
$producten = $database->selectRows("SELECT naam, prijs FROM product");
foreach($producten as $product) {
echo "<p class='pruducten'> Product:" . $product['naam'] . "<br>";
echo "Prijs:" . $product['prijs'] . "</p>";
}
?> 
如果您尝试在 php 代码中打印链接，您可以尝试这样的操作并看看它是否有效吗？
我使用 echo 的原因是它会打印出样式表的代码。如果我将代码直接放入 php 中间而不对其进行回显或将其包装在 '' 中，它将无法正确显示或打印。
'; $email = $database->selectValue("SELECT emailadres FROM klant WHERE naam = 'Bibiche' AND achternaam = 'Laarakkers'"); echo "Het emailadres van Bibiche Laarakkers is $email."; $productInfo = $database->selectSingleRow("SELECT gewicht, prijs, calorieen FROM product WHERE naam = 'Sausage Muffin with Egg Whites'"); echo "Sausage Muffin with Egg Whites
"; echo "Gewicht: " . $productInfo['gewicht'] . "
"; $producten = $database->selectRows("SELECT naam, prijs FROM product"); foreach($producten as $product) { echo ""; echo "Prijs: " . $productInfo['prijs'] . "
"; echo "Aantal Calorieën: " . $productInfo['calorieen'] . "
Product:" . $product['naam'] . "
"; } ?>"; echo "Prijs:" . $product['prijs'] . "
如果这不起作用，因为 css 链接最好在文档的 部分中使用，您可以通过回显代码将代码直接打印到其中，以便它正确地将其打印到页面上。像这样：
.pruducten { font-size:1rem; } '; $email = $database->selectValue("SELECT emailadres FROM klant WHERE naam = 'Bibiche' AND achternaam = 'Laarakkers'"); echo "Het emailadres van Bibiche Laarakkers is $email."; $productInfo = $database->selectSingleRow("SELECT gewicht, prijs, calorieen FROM product WHERE naam = 'Sausage Muffin with Egg Whites'"); echo "Sausage Muffin with Egg Whites
"; echo "Gewicht: " . $productInfo['gewicht'] . "
"; $producten = $database->selectRows("SELECT naam, prijs FROM product"); foreach($producten as $product) { echo ""; echo "Prijs: " . $productInfo['prijs'] . "
"; echo "Aantal Calorieën: " . $productInfo['calorieen'] . "
Product:" . $product['naam'] . "
"; } ?>"; echo "Prijs:" . $product['prijs'] . "
如果您绝对必须用 php 代码打印页面的每个方面，以上就是我的方法。
还有其他方法可以通过直接在 php 文件中使用 html 来实现此目的，例如确保它具有 部分等。但我想沿着您所走的道路努力，以更好地帮助您解决问题。