基本上我已经在我的通用论坛中编辑了“new_topic”页面，以便用户可以从下拉列表中选择帖子的类别，而不是先转到类别并转到新主题，我现在要做的是创建线程时，它不会跳转到标准的“您的新线程是在此处创建的”，而是重定向到该主题所在的类别。
我尝试使用
header( "Location: category.php?id='. $topic_cat . '" );
但是标头已经在其他地方使用。所以我发现了一个在一定程度上有效的元刷新..
echo "<META HTTP-EQUIV='Refresh' Content='0; URL=/category.php?id='. $topic_cat .'>";
但它重定向到“category.phpid=”并输出以下消息。 无法显示类别，请稍后再试。您的SQL语法有误；检查与您的 MySQL 服务器版本相对应的手册，以在第 8 行的 '' 附近使用正确的语法
无论如何我可以使页面跳转到仅在提交函数本身中定义的类别？谢谢你的帮助。
编辑：使用“if”函数可以定义重定向吗？IE。如果以重定向到 category.phpid=2 的形式选择了 topic_cat 2?? 抱歉，我对 PHP 还很陌生，但仍在努力解决所有问题 :( 这是完整的主题创建页面
<?php
//create_topic.php
include 'connect.php';
if($_SESSION['signed_in'] == false)
{
//the user is not signed in
echo 'Sorry, you have to be <a href="/forum/signin.php">signed in</a> to create a topic.';
}
else
{
//the user is signed in
if($_SERVER['REQUEST_METHOD'] != 'POST')
{
//the form hasn't been posted yet, display it
//retrieve the categories from the database for use in the dropdown
$sql = "SELECT
cat_id,
cat_name,
cat_description
FROM
categories";
$result = mysql_query($sql);
if(!$result)
{
//the query failed, uh-oh :-(
echo 'Error while selecting from database. Please try again later.';
}
else
{
if(mysql_num_rows($result) == 0)
{
//there are no categories, so a topic can't be posted
if($_SESSION['user_level'] == 1)
{
echo 'You have not created categories yet.';
}
else
{
echo 'Before you can post a topic, you must wait for an admin to create some categories.';
}
}
else
{
echo '<form method="post" action="">';
echo '<select name="topic_cat">';
while($row = mysql_fetch_assoc($result))
{
echo '<option value="' . $row['cat_id'] . '">' . $row['cat_name'] . '</option>';
}
echo '</select><br />';
echo '<textarea name="post_content" /></textarea><br /><br />
<input type="submit" value="Create topic" />
</form>';
}
}
}
else
{
//start the transaction
$query = "BEGIN WORK;";
$result = mysql_query($query);
if(!$result)
{
//Damn! the query failed, quit
echo 'An error occured while creating your topic. Please try again later.';
}
else
{
//the form has been posted, so save it
//insert the topic into the topics table first, then we'll save the post into the posts table
$sql = "INSERT INTO
topics(topic_subject,
topic_date,
topic_cat,
topic_by)
VALUES('" . mysql_real_escape_string($_POST['post_content']) . "',
NOW(),
" . mysql_real_escape_string($_POST['topic_cat']) . ",
" . $_SESSION['user_id'] . "
)";
$result = mysql_query($sql);
if(!$result)
{
//something went wrong, display the error
echo 'An error occured while inserting your data. Please try again later.<br /><br />' . mysql_error();
$sql = "ROLLBACK;";
$result = mysql_query($sql);
}
else
{
//the first query worked, now start the second, posts query
//retrieve the id of the freshly created topic for usage in the posts query
$topicid = mysql_insert_id();
$sql = "INSERT INTO
posts(post_content,
post_date,
post_topic,
post_by)
VALUES
('" . mysql_real_escape_string($_POST['post_content']) . "',
NOW(),
" . $topicid . ",
" . $_SESSION['user_id'] . "
)";
$result = mysql_query($sql);
if(!$result)
{
//something went wrong, display the error
echo 'An error occured while inserting your post. Please try again later.<br /><br />' . mysql_error();
$sql = "ROLLBACK;";
$result = mysql_query($sql);
}
else
{
$sql = "COMMIT;";
$result = mysql_query($sql);
echo "<META HTTP-EQUIV='Refresh' Content='0; URL=/category.php?id=". $topic_cat ."'>";
}
}
}
}
}
; ?>