PHP id/parent，如何显示所有记录

function displayRecords($records, $parentId = 0, $indent = 0) {
    foreach ($records as $record) {
        if ($record['parent'] == $parentId) {
            echo str_repeat('&nbsp;', $indent * 4) . $record['id'] . '<br>';
            displayRecords($records, $record['id'], $indent + 1);
        }
    }
}

// 假设$records是从数据库中获取的所有记录的数组
$records = [
    ['id' => 1, 'parent' => 0],
    ['id' => 2, 'parent' => 1],
    ['id' => 3, 'parent' => 1],
    ['id' => 4, 'parent' => 2],
    ['id' => 5, 'parent' => 2],
    ['id' => 6, 'parent' => 3],
];

displayRecords($records);