Display and Delete data from database - php

Question

I am new to PHP and just wanting to make a basic page where i can see all the users in the database and delete them. I have come this far but it keeps on telling me that I have an i have and Undefined index: user_id and although it tells me that it has deleted the fields it has not deleted anything. Here is my code:
<?php include_once "includes/scripts.php"; ?>
<?php include_once "includes/connect.php";?>
<?php include_once "includes/cms_page_security.php";?>
<div id="cms_container"><br>
<br>
<h1>MANAGE USERS<img src="images/three_column_grid_line.png" alt="line"></h1>
<p class="logout_btn">Back</p>
<?php
$tbl="users"; // Table name
$sql = "SELECT * FROM $tbl";
$result = mysql_query($sql, $connect);
while($rows = mysql_fetch_array($result)){
?>
<?php
echo $rows['user_id'];
echo $rows['user_name'];
echo $rows['user_password'];
?>
delete
<?php
}
?>
<?php
mysql_close();
?>
</div><!--cms_container-->
</body>
</html>
The page that it should link to that deletes the query:
<?php include_once "includes/connect.php";?>
<?php
$tbl="users";
$user_id= $_GET ['user_id'];
$sql="DELETE FROM $tbl WHERE user_id = '$user_id'";
$result = mysql_query($sql, $connect);
if($result){
echo "Deleted Successfully";
echo "<BR>";
echo "<a href='delete.php'>Back to main page</a>";
}else {
echo "ERROR";
}
?>
<?php
mysql_close();
?>

Answer 1

In delete_user.php you must get user_id
$user_id= $_GET ['id'];
because in your delete link GET variable is "id", not "user_id"

Answer 2

You really should be using PDO instead.
The issue is in the information that you are passing.
The link : delete
is looking for an 'id' but you're later looking for 'user_id'
If you change it to delete, it should work.
I still strongly suggest you look into PDO instead though, it's much more secure and easier to work with.
Example of PDO Delete
public function deleteUser($username, $user_id){
if($this->isAdmin($username) == true){
$query = $this->db->prepare('DELETE FROM users WHERE user_id = ?');
$query->bindValue(1, $user_id);
try{
$query->execute();
}catch(PDOException $e){
die($e->getMessage());
}
}else{
return false;
}
}
I'm running an extra check to make sure the person who is requesting the deletion is an admin member but you should be able to see the structure

Answer 3

In addition to the other answers:
It looks like this line could be a fatal error, if php short tags aren't enabled:
delete
The php manual says:
*PHP also allows for short tags <? and ?>
(which are discouraged because they are only available if enabled with
short_open_tag php.ini configuration file directive, or if PHP was configured
with the--enable-short-tags option.*
http://php.net/manual/en/language.basic-syntax.phptags.php

Answer 4

The SQL query will be successful even if it alters zero rows. You are prefixing your user ids with a space when you are generating your HTML (id= <?), so you aren't matching any rows (since "1" won't be matched by " 1").

Answer 5

Where you are creating your 'Delete' link
delete
You're creating a variable of 'id', but later you look for 'user_id.
Change your link to
delete