Remove Current Row without ID (PHP, MYSQL, HTML) - php

Question

I am working on a HTML website. I am using a MySQL Database and PHP.
The concept so far is fairly simple:
The user can add some text onto the site by clicking on an add button - the user gets directed to a page with a dialogue box
When he clicks submit, that text is in the data base.
The PHP code knows: while the data base has entries -> echo the text onto the HTML website (I added a while loop)
Now my next step is to let the user delete the text. I added a trash can glyphicon onto the HTML site. When the user clicks it, I would like for the current row in the table to be removed. Unfortunately nothing happens!
Here's the code:
<?php
$query = " SELECT * FROM Thesis";
$sql = mysqli_query($conn, $query);
$count = mysqli_num_rows($sql);
while ($row = mysqli_fetch_array($sql)){
?>
<div class="box green-box">
<p><div class="center-box-content">
<!--echo the title -->
<?php echo $row["title"]; ?>
<br>
<!--echo the description -->
<?php echo $row["description"]; ?>
</p>
<div class="lower-right-box-content">
<a href="adminview.php">
<span class="glyphicon glyphicon-trash glyphicon-trash" role="button">
<?php
$delquery = " DELETE * FROM Thesis";
mysqli_query($conn, $delquery);
?>
</span>
</a>
</div>
</div>
</div>
<?php };
?>
What am I doing wrong? I know that the main mistake must lie somewhere
in $delquery. But I am lost.
I also know that it would be better to have an ID for each row. But I would like to avoid it, because since we are in a while loop, there must be a way to just delete the current row that the while loop is in, right? That would be my preferred solution.
Lastly, I am very new to programming and not the most elegant programmer yet, please be kind :)

Answer 1

You are going to want a simple ID for your thesis table, something like this:
CREATE TABLE `Thesis` (
`thesis_id` int(11) unsigned NOT NULL AUTO_INCREMENT,
`title` varchar(255) NOT NULL,
`description` varchar(255) NOT NULL,
PRIMARY KEY (`thesis_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
I would separate out the PHP from the display code, putting the PHP code at the top of your file. For security and better code, I would use bind variables with PDO (instead of mysqli). But sticking with your original code, I would rewrite it like this:
<?php
// Establish the connection
$sql = mysqli_query($conn, $query);
// Delete a specific element
if (isset($_GET['delete_id']) && $_GET['delete_id'] > 0) {
$query = "DELETE FROM Thesis WHERE thesis_id = " . $_GET['delete_id'];
mysqli_query($conn, $query);
}
// Gather all the rows
$query = "SELECT * FROM Thesis";
$count = mysqli_num_rows($sql);
$rows = [];
while ($row = mysqli_fetch_array($sql)){
$rows[] = $row;
}
?>
<?php foreach ($rows as $row): ?>
<div class="box green-box">
<p><div class="center-box-content">
<!--echo the title -->
<?= $row["title"] ?>
<br>
<!--echo the description -->
<?= $row["description"] ?>
</p>
<div class="lower-right-box-content">
<a href="adminview.php?delete=<?= $row['thesis_id'] ?>">
<span class="glyphicon glyphicon-trash glyphicon-trash" role="button"></span>
</a>
</div>
</div>
</div>
<?php endforeach; ?>
The foreach call above is a common PHP shortcut, and the <?= tag will echo back something without having to call echo. The deletion of element using a GET call is not recommended, but for simplicity I'm keeping it in place.

Answer 2

WARNING: BE CAREFUL OF SQL INJECTIONS!!
Now, back to the problem.
First of all, your delete SQL code is run every time a row is inserted, so you will never have rows. First step is to delete
<?php
$delquery = " DELETE * FROM Thesis";
mysqli_query($conn, $delquery);
?>
Next, you want that certain row to be deleted if the user clicks the trash icon. To do this, you can pass the row ID to a PHP page via <a> or $.ajax, then delete it from that PHP page. However, BE CAREFUL OF SQL INJECTIONS
So you would need on your main page:
[delete icon]
And on your deleteRow.php:
$id=$_GET['id'];
//anti-injection code
mysqli_query($conn,"DELETE FROM Thesis WHERE id='$id'");

Answer 3

<a href="adminview.php">
<span class="glyphicon glyphicon-trash glyphicon-trash" role="button">
<?php
$delquery = " DELETE * FROM Thesis";
mysqli_query($conn, $delquery);
?>
</span>
</a>
In above code you deleting all the rows. which is wrong. what you should do is:
<a href="adminview.php?id=<?php echo $row["id"];?>">
<span class="glyphicon glyphicon-trash glyphicon-trash" role="button"></span>
</a>
in adminview.php
if(isset($_REQUEST['id'])) {
$delquery = " DELETE FROM Thesis WHERE id= '".$_REQUEST['id']."' ";
mysqli_query($conn, $delquery);
}