Why can't I "INSERT INTO" my table through my php script? - php

Question

I have two different directories on my wampserver, this code works on one, but not on the other, I don't understand why.
PHP
<?php
error_reporting(E_ALL & ~E_NOTICE);
session_start();
$msg = "";
if (!isset($_SESSION['username'])) {
header('Location: login.php');
die();
}
if(isset($_SESSION['username'])) {
if (isset($_POST['submit']))
{
$className = $_POST['className'];
$classColour = $_POST['classColour'];
include_once("connection.php");
$sql = "INSERT INTO class (className, classColour) VALUE ('$className', '$classColour')";
mysqli_query($dbConnection, $sql);
$msg = "New class '" . $className . "' added.";
} else {
$msg = "No class added yet.";
}
}
?>
HTML
<form method="post" action="add_class.php">
<input type="text" name="className" placeholder="Class" />
<input type="text" name="classColour" placeholder="Colour" />
<div><input type="submit" name="submit" value="Add" class="btn butn-orange"/></div>
</form>
This is in the file "add_class.php" and I've tried many different things, putting single quotes (`) around the table columns in the $sql but still, it won't work. I've tried adjusting the names in the table, which had underscores but now have camelCasing, still made no difference. This code works perfectly in another directory, can someone please tell me why this is happening and possibly propose a solution? Thank you in advance.
P.S My connection works because I inserted a new row via phpmyadmin and looped through the database printing every existing "className" and it worked, I just can't insert from the php script.
connection.php
<?php
$dbConnection = mysqli_connect("localhost","root", "", "main");
if(mysqli_connect_errno())
{
echo "Failed to connect" . mysqli_connect_error();
}
?>

Answer 1

When asked if you've had assigned the sessions, you replied I assigned this when the user logs in. Moving forward from that, let's assume the assigned session as one written below:
<?php
error_reporting(E_ALL & ~E_NOTICE);
session_start();
$_SESSION['username'] = "HawqasKaPujaari";
$msg = "";
// this fails, as session is already set.
if (!isset($_SESSION['username'])) {
header('Location: login.php');
die();
}
if(isset($_SESSION['username'])) {
if (isset($_POST['submit']))
{
$className = $_POST['className'];
$classColour = $_POST['classColour'];
include_once("connection.php");
$sql = "INSERT INTO class (className, classColour) VALUES ('$className', '$classColour')";
mysqli_query($dbConnection, $sql);
echo $msg = "New class '" . $className . "' added.";
} else {
$msg = "No class added yet.";
}
}
?>
<form method="post" action="">
<input type="text" name="className" placeholder="Class" />
<input type="text" name="classColour" placeholder="Colour" />
<div><input type="submit" name="submit" value="Add" class="btn butn-orange"/></div>
</form>
Note: The only changes I made were to change the action="" empty and changed VALUE to VALUES in your query.
connection.php:
<?php
$dbConnection = mysqli_connect("localhost","root", "", "main");
if(mysqli_connect_errno())
{
echo "Failed to connect" . mysqli_connect_error();
}
?>
As the above posted code seemed to be correct and was bugging me so I thought of testing it myself by creating the database/tables and it seemed to work properly without any errors. I have posted the relevant pictures below:
Note: Make sure you have the connection.php file in the same
directory as the add_class.php.