首页中添加了updateentry.php链接，但是跳转之后又回到首页？

[磐创 AI]

附inde.php代码和updateentry.php代码

<?php

require("header.php");

$sql="SELECT entries.*,categories.cat 
FROM entries,categories
WHERE entries.cat_id=categories.id
ORDER BY dateposted DESC
LIMIT 1;";
$result=mysql_query($sql);
$row=mysql_fetch_assoc($result);

echo"<h2><a href='viewentry.php?id=".$row['id']."'>".$row['subject']."</a></h2><br />";
echo"<i>In<a href='viewcat.php?id=".$row['cat_id']."'>".$row['cat']."</a>-posted on". date("D jS F Y g.iA",strtotime($row['dateposted']))."</i>";


if(isset($_SESSION['USERNAME'])==true){
	echo"[<a href='updateentry.php?id=".$row['id']."'>edit</a>]";
}


echo"<p>";
echo nl2br($row['body']);
echo"</p>";

echo"<p>";
$commsql="SELECT name 
FROM comments 
WHERE blog_id=".$row['id']."
ORDER BY dateposted;";
$commresult=mysql_query($commsql);
$numrows_comm=mysql_num_rows($commresult);
if($numrows_comm==0){
echo"<p>No comments.</p>";
}
else{
echo"(<strong>".$numrows_comm."</strong>)comments:";
$i=1;
while($commrow=mysql_fetch_assoc($commresult)){
echo"<a href='viewentry.php?id=".$row['id']."#comment".$i."'>".$commrow['name']."</a>";
$i++;
}
}
echo"</p>";



$prevsql = "SELECT entries.*,categories.cat FROM entries,categories
WHERE entries.cat_id=categories.id
ORDER BY dateposted DESC
LIMIT 1,5;";
$prevresult=mysql_query($prevsql);
$numrows_prev=mysql_num_rows($prevresult);
if($numrows_prev==o){
	echo"<p>No previous entries.</p>";
}
else{
	echo"<ul>";
	
	while($prevrow = mysql_fetch_assoc($prevresult)){
		echo"<li><a href='viewentry.php?id=" . $prevrow['id'] . "'>". $prevrow['subject'] ."</a></li>";
		
	}
}
echo"</ul>";

require("footer.php");

/*
$prevsql = "SELECT entries.*, categories.cat FROM entries, categories
WHERE entries.cat_id = categories.id
ORDER BY dateposted DESC
LIMIT 1, 5;";
$prevresult = mysql_query($prevsql);
$numrows_prev = mysql_num_rows($prevresult);

if($numrows_prev == 0) {
	echo "<p>No previous entries.</p>";
}
else {

	echo "<ul>";

	while($prevrow = mysql_fetch_assoc($prevresult)) {
		echo "<li><a href='viewentry.php?id=" . $prevrow['id'] . "'>" . $prevrow	['subject'] . "</a></li>";
	}
}

echo "</ul>";

require("footer.php");

*/
?>

<?php

session_start();
require("config.php");



if(isset($_SESSION['USERNAME']) == FALSE) {
	header("Location: " . $config_basedir);
}



$db = mysql_connect($dbhost, $dbuser, $dbpassword);
mysql_select_db($dbdatabase, $db);



if(isset($_GET['id']) == TRUE) {
	if(is_numeric($id) == FALSE) {
		$error = 1;
	}

	if($error == 1) {
		header("Location: " . $config_basedir);
	}
	else {
		$validentry = $_GET['id'];
	}
}
else {
	$validentry = 0;
}

if($_POST['submit']) {
	$sql = "UPDATE entries SET cat_id = " . $_POST['cat'] . ", subject = '" . $_POST['subject'] ."', body = '" . $_POST['body'] . "' WHERE id = " . $validentry . ";";
	mysql_query($sql);
	
header("Location: " . $config_basedir . "/viewentry.php?id=".$validentry);
	
}
else {

	require("header.php");

	$fillsql = "SELECT * FROM entries WHERE id = " . $validentry . ";";	
	$fillres = mysql_query($fillsql);
	$fillrow = mysql_fetch_assoc($fillres);

?>
<h1>Update Entry</h1>
<form action="<?php echo $SCRIPT_NAME . "?id=" . $validentry; ?>" method="post">

<table>
<tr>
	<td>Category</td>
	<td>
	<select name="cat">
	<?php
		$catsql = "SELECT * FROM categories;";
		$catres = mysql_query($catsql);
		while($catrow= mysql_fetch_assoc($catres)) {
			echo "<option value='" . $catrow['id'] . "'";
			
			if($catrow['id'] == $fillrow['cat_id']) {
				echo " selected";
			}
			
			echo ">" . $catrow['cat'] . "</option>";
		}
	?>
	</select>
	</td>
</tr>
<tr>
	<td>Subject</td>
	<td><input type="text" name="subject" value="<?php echo $fillrow['subject']; ?>"></td>
</tr>
<tr>
	<td>Body</td>
	<td><textarea name="body" rows="10" cols="50"><?php echo $fillrow['body']; ?></textarea></td>
</tr>
<tr>
	<td></td>
	<td><input type="submit" name="submit" value="Update Entry!"></td>
</tr>
</table>
</form>

<?php
}
require("footer.php");
?>
	
	
	

[磐创 AI]

代码来自：php+mysql八大动态web应用实践

[motein]

你的session_start()是不是在header.php第一行？另外你的username是在哪段代码里赋值的?我觉得你是没给他username这个变量赋值。跳转是一个简单的动作，你也可以用js代码试试。

[coder]

深刻的理解一下
header("Location: " .
的作用。
以及后边跟的具体的字符串是什么。就知道为什么跳到首页了