为什么这段代码不能在CodeIgniter中运行？

Question

查询代码：

$query = $this->db->query(
    'SELECT course.*, AVG(course_review.`rating`) AS `avg_rating`
     FROM course
     LEFT JOIN course_review ON `course`.`id` = `course_review`.`course_id`
     WHERE `course`.`course_category`= ' . $id . '
       AND `course`.`approved`= 3
       AND `course`.`delete_course` != 1
       AND `course`.`unpublish_course` != 1
     GROUP BY `course`.`id`
     ORDER BY avg_rating DESC');

return $query->result()

由于

Answer 1

您可以针对您的问题尝试此查询：

<强>查询： -

$query = $this->db->query('SELECT
  course.id,
  AVG(course_review.rating) AS avg_rating
FROM course
LEFT JOIN course_review
  ON course.id = course_review.course_id
WHERE course.course_category = ' . $id . '
AND course.approved = 3
AND course.delete_course != 1
AND course.unpublish_course != 1
GROUP BY course.id
ORDER BY avg_rating DESC');

return $query->result();