所以我遇到的问题是我在书中做的这个基本数据库应用程序练习。基本上，当您尝试将产品添加到数据库中时，如下面的代码所示，它会进行检查以确保所有字段都已填写完毕。但是，在执行查询的最后，当我有include（'home.php'）时，会发生这样的情况：当我返回到home.php页面并单击该页面上的一个链接时，如果其中一个字段为空，我会得到错误。有什么想法吗？
<?php
// Get the product data
$category_id = $_POST['category_id'];
$code = $_POST['code'];
$name = $_POST['name'];
$price = $_POST['price'];
// Validate inputs
if (empty($code) || empty($name) || empty($price) ) {
$error = "Invalid product data. Check all fields and try again.";
include('error.php');
} else {
// If valid, add the product to the database
require_once('database.php');
$query = "INSERT INTO products
(categoryID, productCode, productName, listPrice)
VALUES
('$category_id', '$code', '$name', '$price')";
$db->exec($query);
// Display the Product List page
include('home.php') ;
}
?>
没有html/css 的home.php
<?php
require_once('database.php');
// Get category ID
if(!isset($category_id)) {
$category_id = $_GET['category_id'];
if (!isset($category_id)) {
$category_id = 1;
}
}
// Get name for current category
$query = "SELECT * FROM categories WHERE categoryID = $category_id";
$category = $db->query($query);
$category = $category->fetch();
$category_name = $category['categoryName'];
// Get all categories
$query = "SELECT * FROM categories ORDER BY categoryID";
$categories = $db->query($query);
// Get products for selected category
$query = "SELECT * FROM products
WHERE categoryID = $category_id
ORDER BY productID";
$products = $db->query($query);
?>
在文件home.php中，使用$_GET而不是$_POST:
更改此项：
$category_id = $_GET['category_id'];
收件人：
$category_id = $_POST['category_id'];