How to get data from mysql to the select option in php - php

Question

I have 2 tables: Students and Classes. In table Classes, I have a column "name" and in table Students I have a column "class" with input as select option. I want to get data from "name" to the select option. Anyone can help me?
This is my source code:
<?php
include "connect.php";
if (isset($_GET['id'])) {
$id = $_GET['id'];
$sqlClass = "select * from classes where id = $id";
$result = $conn->query($sqlClass);
if ($result->num_rows > 0) {
$classes[] = $result->fetch_assoc();
} else{
die('class not found');
}
}
$sql = "select count(name) from classes";
$total = $conn->query($sql);
$totalClass = $total->fetch_assoc()['count(name)'];
?>
<div class="form-group">
<label for="">Class</label>
<select name="" id="input" class="form-control" required="required">
<?php
for ($i=1; $i <= $totalClass ; $i++) {
?>
<option value="<?=$i?>"><?php echo $classes['name']; ?></option>
<?php } ?>
</select>
</div>

Answer 1

Your select needs a name (if you don't name it you will never find it when you post the data) and you don't need the second query to get a count, just an iterator for each option:
<?php
include "connect.php";
if (isset($_GET['id'])) {
$id = $_GET['id'];
$sqlClass = "select * from classes where id = $id";
$result = $conn->query($sqlClass);
if ($result->num_rows > 0) {
$classes[] = $result->fetch_assoc();
} else{
die('class not found');
}
}
?>
<div class="form-group">
<label for="">Class</label>
<select name="A_NAME_IS_REQUIRED" id="input" class="form-control" required="required">
<?php
$i = 1;
foreach($classes AS $class) {
?>
<option value="<?=$i?>"><?php echo $class['name']; ?</option>
<?php
$i++;
}
?>
</select>
</div>
In addition, you will want to check if $classes is an array. If it isn't there would be no sense in creating the drop-down.
SQL Injection Warning!
Little Bobby says your script is at risk for SQL Injection Attacks. Learn about prepared statements for MySQLi. Even escaping the string is not safe!