我可以跳过此类查询的查询类吗？

Question

如果我将传入的参数转换为整数，或者我是否还需要使用查询类，下面的查询是否会被视为“注入安全”？

public function get_chapters_by_course($course_id = NULL)
{
  $course_id = (int)$course_id; // is it sanitised yet?

  $query = $this->db->query("
  SELECT
    chapters.id AS id,
    chapters.chapter_order AS chapter_order,
    chapters.title AS title,
    chapters.description AS description,
    length(chapters.tutorial) AS tutorial_length,
    chapters.course_id AS course_id,
    (SELECT count(sentences.id) FROM sentences WHERE sentences.chapter_id = chapters.id) AS total_sentences,
    (SELECT user_id FROM courses WHERE id = $course_id ) AS course_owner
  FROM chapters
  WHERE chapters.course_id = $course_id
  ");

  return $query->result();
}

感谢。