Php error displaying data in input - php

Question

This piece of code is working fine, what I want to is why if I remove the foreach($rows as $row) I gt an error, is there a way to display the data without using it.
<?php
require("coneccion.php");
if(empty($_SESSION['user']))
{
header("Location: index.php");
die("Redirecting to index.php");
}
$id = $_GET['id'];
$nombre = $_SESSION['user']['username'];
$query = "SELECT c.coursename FROM courses as c WHERE c.courseid = $id and c.id = (SELECT id FROM users WHERE username = '$nombre') ";
try
{
$stmt = $db->prepare($query);
$stmt->execute();
}
catch(PDOException $ex)
{
die("Error");
}
$rows = $stmt->fetchAll();
?>
<?php
foreach($rows as $row):
echo '<input type="text" name="coursename" value="' .htmlentities($row['coursename']) . '" />';
endforeach;

Answer 1

Assuming you're working with the standard PDO settings, you can access the first returned result like so:
echo '<input type="text" name="coursename" value="' .htmlentities($rows[0]['coursename']) . '" />';

Answer 2

To return the first row in your array you could do:
echo '<input type="text" name="coursename" value="'
.htmlentities($rows[0]['coursename']) . '" />';
Which will return the first row, but I dont recommend this. PHP array are hashtables they are incredibly fast you don't save yourself any style points by making your code less maintainable.