PHP selectタグで変数格納 #PHP

select.php
<?php

$selected_value = '';

if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    if (isset($_POST['my_select'])) {
        $selected_value = $_POST['my_select'];
        echo "選択された値: " . $selected_value;
    } else {
        echo "値が選択されていません。";
    }
}

$html = <<<EOT
<!DOCTYPE html>
<html>
<head>
    <title>PHP Select Example</title>
</head>
<body>
    <form action="{$_SERVER['PHP_SELF']}" method="post">
        <select name="my_select">
            <option value="option1">オプション1</option>
            <option value="option2">オプション2</option>
            <option value="option3">オプション3</option>
        </select>
        <input type="submit" value="送信">
    </form>
</body>
</html>
EOT;

echo $html;
?>