我正在开发一个自定义的 MySQL 和 PHP 论坛，我正试图让我的主题在它们各自的类别下就座/列出。当我在管理面板中创建主题时，我可以设置类别 ID，它与类别的 ID 相对应。我已经在网上和这里的网站上浏览了很多。
我已经能够让类别显示出来，并且已经能够确定主题所在的位置，但是主题没有显示，我传递的参数一直导致 null，并导致每个类别都表明没有创建主题。
这是我正在处理的功能:
function fetch_forum() {
global $connection;
$query = "SELECT * FROM forum_categories LEFT JOIN forum_topics ON forum_topics.forum_topic_category_id = forum_categories.forum_category_id";
$select_forum_data = mysqli_query($connection, $query);
$new_topic = "";
$pre_topic = "";
while($row = mysqli_fetch_assoc($select_forum_data)) {
$forum_topic_id = $row['forum_topic_id'];
$forum_topic_title = $row['forum_topic_title'];
$forum_topic_description = $row['forum_topic_description'];
$forum_topic_category_id = $row['forum_topic_category_id'];
$forum_category_id = $row['forum_category_id'];
$forum_category_title = $row['forum_category_title'];
$new_topic = $forum_topic_title;
if($forum_category_title != null) {
echo "<thead>";
echo "<tr>";
echo "<th><span class='glyphicon glyphicon-file' aria-hidden='true'></span> {$forum_category_title}</th>";
echo "<th>Topics</th>";
echo "<th>Posts</th>";
echo "<th>Last Post</th>";
echo "</tr>";
echo "</thead>";
}
if($new_topic != $pre_topic) {
echo "<tbody>";
echo "<tr>";
echo "<td><a href='topic.php?t_id=<?php echo $forum_topic_id; ?>'><h5> {$forum_topic_title}</h5></a></td>";
echo "<td>1</td>";
echo "<td>1</td>";
echo "<td>03-28-2017</td>";
echo "</tr>";
echo "</tbody>";
} else {
echo "<tbody>";
echo "<tr>";
echo "<td>No topics have been created</td>";
echo "</tr>";
echo "</tbody>";
}
$pre_topic = $forum_topic_title;
}
}
这是我的索引页:
<?php include "includes/header.php"; ?>
<?php include "includes/db.php"; ?>
<!-- Navigation -->
<?php include "includes/navigation.php"; ?>
<!-- Page Content -->
<div class="container">
<div class="row">
<!-- Blog Entries Column -->
<div class="col-md-8">
<!-- Forum Navigation -->
<?php include "includes/forum_navigation.php"; ?>
<!-- First Blog forum -->
<table class="table table-hover">
<?php fetch_forum(); ?>
</table>
<hr>
</div>
<!-- Blog Sidebar Widgets Column -->
<?php include "includes/sidebar.php"; ?>
</div>
</div>
<!-- /.row -->
<hr>
<?php include "includes/footer.php"; ?>
这是我的页眉:
<?php ob_start(); ?>
<?php session_start(); ?>
<?php include "functions.php"; ?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta name="description" content="">
<meta name="author" content="">
<title>My CMS Framework</title>
<!-- Bootstrap Core CSS -->
<link href="../css/bootstrap.min.css" rel="stylesheet">
<!-- Custom CSS -->
<link href="../css/blog-home.css" rel="stylesheet">
<link href="../css/style.css" rel="stylesheet">
<!-- Custom Fonts -->
<link href="../admin/font-awesome/css/font-awesome.min.css" rel="stylesheet" type="text/css">
<!-- HTML5 Shim and Respond.js IE8 support of HTML5 elements and media queries -->
<!-- WARNING: Respond.js doesn't work if you view the page via file:// -->
<!--[if lt IE 9]>
<script src="https://oss.maxcdn.com/libs/html5shiv/3.7.0/html5shiv.js"></script>
<script src="https://oss.maxcdn.com/libs/respond.js/1.4.2/respond.min.js"></script>
<![endif]-->
<script type="text/javascript" src="../../js/autoBreadcrumbs.js"></script>
</head>
<body>
最佳答案
FWIW 你的代码对我有用并产生:
使用这个假定的数据库结构和数据集。 
会不会只是你的测试数据集有问题？
关于php - 自定义 MySQL 和 PHP 论坛 - 在类别下列出主题，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/44031081/