Trying to Delete the data displayed in my tables - php

Question

I have been able to display the data from my database on to my website and I'm trying to delete a single row.
Now the button works but it completely deletes everything as you may tell from the code.
I have no idea on how to assign the delete button to a specific row in my table, where it just deletes that data in that specific row.
On top of this I have one delete button that sits upon my table and have no clue on how to set separate delete buttons for each row given.
admin.php (Displaying my data)
<?php
echo "<table style='box'>";
echo "<tr><th>ID</th><th>First Name</th><th>Last Name</th><th>Role</th>
<th>Email</th><th>Username</th><th>Delete</th><th>Amend</th></tr>";
class TableRows extends RecursiveIteratorIterator {
function __construct($it) {
parent::__construct($it, self::LEAVES_ONLY);
}
function current() {
return "<td style='box'>" . parent::current(). "</td>";
}
function beginChildren(){
echo "<tr>";
}
function endChildren(){
echo "</tr>";
}
}
require 'connection.php';
try {
$stmt = $conn->prepare("SELECT id, FirstName, LastName, Role, Email, Username FROM users");
$stmt->execute();
$result = $stmt->setFetchMode(PDO::FETCH_ASSOC);
foreach(new TableRows(new RecursiveArrayIterator($stmt->fetchAll())) as $k=>$v){
echo $v;
}
}
catch (PDOException $e){
echo "Error: " . $e->getMessage();
}
$conn = null;
?>
<form method="post" action="delete.php">
<input <input class="btn-default" type="submit" name="login" value="Delete">
</form>
<?php
echo "</table>";
?>
delete.php
<?php
$servername = 'localhost';
$username = 'root';
$pass = 'root';
$database = 'tutor_database';
try {
$conn = new PDO("mysql:host=$servername;dbname=$database", $username, $pass);
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
//sql to delete record.
$sql = "DELETE FROM users WHERE id = id";
$conn->exec($sql);
echo "Record deleted!";
} catch(PDOException $e) {
echo $sql . "<br>" . $e->getMessage();
}
$conn = null;
?>
I would show an image but I don't have enough reputation points to display it.

Answer 1

The WHERE clause in your DELETE statement will always return to true. On every row, ID will always equal ID. Hence, everything is deleted. You need to pass a parameter to delete script to filter on the row you want deleted. You can do so by a hidden HTML input value using get="method" of <form>.
However, the key is how to obtain that id from webpage's select query. Additionally, you will want to put the input button at the end of each row to delete the corresponding row's id. For these two items, you might have to return to traditional loop onto web page instead of the RecursiveArrayIterator() because we need to add a non fetched object (form delete button) into table.
admin.php (notice form button as last table cell of each row)
...same code as above...
try {
$stmt = $conn->prepare("SELECT id, FirstName, LastName, Role, Email, Username FROM users");
$stmt->execute();
$result = $stmt->setFetchMode(PDO::FETCH_ASSOC);
while($row = $result->fetch()) {
?>
<tr>
<td style="box"> <?php echo $row['id']; ?></td>
<td style="box"> <?php echo $row['FirstName']; ?></td>
<td style="box"> <?php echo $row['LastName']; ?></td>
<td style="box"> <?php echo $row['Role']; ?></td>
<td style="box"> <?php echo $row['Email']; ?></td>
<td style="box"> <?php echo $row['Username']; ?></td>
<td>
<form method="get" action="delete.php">
<input type="hidden" name="rowid" value="<?php echo $row['id']; ?>">
<input class="btn-default" type="submit" name="login" value="Delete">
</form>
</td>
<tr>
<?php
}
}
catch (PDOException $e){
echo "Error: " . $e->getMessage();
}
$conn = null;
delete.php (notice $id generated from $GET() and used in delete query)
$servername = 'localhost';
$username = 'root';
$pass = 'root';
$database = 'tutor_database';
try {
$conn = new PDO("mysql:host=$servername;dbname=$database", $username, $pass);
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
// OBTAIN ROWID FROM $_GET
if(isset($_GET['rowid'])) {
$id = $_GET['rowid'];
}
// DELETE SPECIFIED ROW
$sql = "DELETE FROM users WHERE id = ".$id;
$conn->exec($sql);
echo "Record deleted!";
} catch(PDOException $e) {
echo $sql . "<br>" . $e->getMessage();
}
$conn = null;

Answer 2

Trying to follow what you have. Have you tried setting the id to a var before doing?
$sql = "DELETE FROM users WHERE id = id";
Example:
$sql = "DELETE FROM users WHERE id = '$id'";

Answer 3

One problem is that your DELETE statement does not include a variable.
//sql to delete record.
$sql = "DELETE FROM users WHERE id = id";
You need something more like:
//sql to delete record.
$sql = "DELETE FROM users WHERE id = " . $id;
where $id is defined with the ID of the selected row.
Let's address another "hidden" problem.
Now the button works but it completely deletes everything as you may tell from the code.
Given the fact that you said this deletes ALL the records, I would guess that the id of each of your rows is the string 'id' and not a unique integer value.
DELETE FROM {table} WHERE id = {number} does not delete ALL records. It only deletes records matching the condition. You should make sure that you are setting id's correctly when adding rows. The id column should have the following properties: INT UNSIGNED NOT NULL AUTO_INCREMENT.