PHP will not delete from MySQL

For some reason, JavaScript/PHP wont delete my data from MySQL! Here is the rundown of the problem.

I have an array that displays all my MySQL entries in a nice format, with a button to delete the entry for each one individually. It looks like this:

<?php

            include("login.php");

        //connection to the database
        $dbhandle = mysql_connect($hostname, $username, $password)
         or die("<br/><h1>Unable to connect to MySQL, please contact support at [email protected]</h1>");

        //select a database to work with
        $selected = mysql_select_db($dbname, $dbhandle)
          or die("Could not select database.");

        //execute the SQL query and return records
        if (!$result = mysql_query("SELECT `id`, `url` FROM `videos`"))
        echo 'mysql error: '.mysql_error();

        //fetch tha data from the database
        while ($row = mysql_fetch_array($result)) {
           ?>

       <div class="video"><a class="<?php echo $row{'id'}; ?>" href="http://www.youtube.com/watch?v=<?php echo $row{'url'}; ?>">http://www.youtube.com/watch?v=<?php echo $row{'url'}; ?></a><a class="del" href="javascript:confirmation(<? echo $row['id']; ?>)">delete</a></div>

<?php }

//close the connection
mysql_close($dbhandle);
?>

The delete button has an href of javascript:confirmation(<? echo $row['id']; ?>) , so once you click on delete, it runs this:

<script type="text/javascript">
<!--
function confirmation(ID) {
    var answer = confirm("Are you sure you want to delete this video?")
    if (answer){
        alert("Entry Deleted")
        window.location = "delete.php?id="+ID;
    }
    else{
        alert("No action taken")
    }
}
//-->
</script>

The JavaScript should theoretically pass the 'ID' onto the page delete.php. That page looks like this (and I think this is where the problem is):

<?php

include ("login.php");

mysql_connect($hostname, $username, $password)
 or die("Unable to connect to MySQL");

mysql_select_db ($dbname)
or die("Unable to connect to database");

mysql_query("DELETE FROM `videos` WHERE `videos`.`id` ='.$id.'");
echo ("Video has been deleted.");
?>

If there's anyone out there that may know the answer to this, I would greatly appreciate it. I am also opened to suggestions (for those who aren't sure).

谢谢！

看答案

在你的 delete.php script, you are using this line :

mysql_query("DELETE FROM `videos` WHERE `videos`.`id` ='.$id.'");

这 $id variable doesn't exists : you must initialize it from the $_GET variable, like this :

$id = $_GET['id'];

(This is because your page is called using an HTTP GET request -- ie, parameters are passed in the URL)

Also, your query feels quite strange : what about this instead :

mysql_query("DELETE FROM `videos` WHERE `videos`.`id` = '$id' ");

ie, removing the '.' : you are inside a string already, so there is nothing to concatenate （这 dot operator in PHP is for concatenation of strings)

笔记：

if this works on some server, it is probably because of register_globals
- For more informations, see Using Register Globals
- But note that this "feature" has been deprecated, and should definitely not be used !
  - It causes security risks
  - And should disappear in PHP 6 -- that'll be a nice change, even if it breaks a couple of old applications
your code has a big SQL注射 hole : you should sanitize/filter/escape the $id before using it in a query !
- 如果你 video.id is a string, this means using mysql_real_escape_string
  - If you where using the mysqli or PDO extensions, you could also take a look at prepared statements
- with an integer, you might call intval to make sure you actually get an integer.

So, in the end, I would say you should use something that looks like this :

$id = $_GET['id'];
$escaped_id = mysql_real_escape_string($id);
$query = "DELETE FROM `videos` WHERE `videos`.`id` = '$escaped_id'";
// Here, if needed, you can output the $query, for debugging purposes
mysql_query($query);

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