Delete Button in PHP isn't Working - php

Question

I'm trying to add a php button on to my site, however it doesn't seem to be working.
The delete php script is;
if(isset($_POST["delete"])) {
$delquery = "DELETE FROM emails WHERE ID=$_POST["delete"]";
mysqli_query($connection, $delquery);
}
And the form looks like which is on the same file;
<form action="email-response.php" method="post">
<input type="hidden" name="hidden" value="<?php echo $row['ID']; ?>">
<input type="submit" name="delete" value="delete">
</form>
However whenever I clicked the delete button nothing is happening.
In relation to the reply saying that my $connection function is wrong, here is the function however its working as it is fetching my information for my posts.
define("DB_SERVER", "myservername");
define("DB_USER", "myusername"); //username
define("DB_PASS", "mypassword"); //password
define("DB_NAME", "mydbname"); // database name
$connection = mysqli_connect(DB_SERVER, DB_USER, DB_PASS, DB_NAME);
if(mysqli_connect_errno()) {
die("Database connection failed: " .
mysqli_connect_error() .
" (" . mysqli_connect_errno() . ")"
);
} else {
echo "connected";
}

Answer 1

The element you wish to delete is named hidden and not delete.
That is what your submit button is named as (delete).
Change your query to this:
if(isset($_POST["delete"]) && !empty($_POST["hidden"])){
$id = mysqli_real_escape_string($connection, $_POST["hidden"]);
}
$delquery = "DELETE FROM emails WHERE ID='$id'";
mysqli_query($connection, $delquery) or die(mysqli_error($connection));
if(mysqli_affected_rows($connection)){
echo "It was really successful.";
}
isset($_POST["delete"]) is to check if the submit button was clicked.
Using mysqli_affected_rows() will show you if your query was truly successful.
This is a function I've grown to use more often.
Add error reporting to the top of your file(s) which will help find errors.
<?php
error_reporting(E_ALL);
ini_set('display_errors', 1);
// rest of your code
Sidenote: Error reporting should only be done in staging, and never production.
Sidenote: Using your present method, leaves you open to SQL injection.
Use mysqli with prepared statements, or PDO with prepared statements, they're much safer.

Answer 2

Your connection is good.
Here is the solution which will work and is simple:
Your form:
<form action="#" method="post">
<input type="hidden" name="to_delete" value="<?php echo $row['ID']; ?>">
<input type="submit" name="delete" value="delete">
</form>
Your delete script:
if(isset($_POST["delete"]))
{
$delquery = "DELETE FROM user WHERE ID=".$_POST['to_delete']."";
mysqli_query($connection, $delquery);
}