復雜的聯接查詢軌道

Question

SELECT course_categories.course_category_title, COUNT(*) as count
FROM course_enrollments
JOIN courses ON course_enrollments.course_id = courses.course_id
JOIN course_categories ON course_categories.id = courses.course_category_id"
GROUP BY course_categores.id
ORDER BY courses_categories.title

我將如何在Rails中執行此操作：（我嘗試了以下重大錯誤）

category_rs = CourseEnrollment.select("course_categories.title, COUNT(*) as count").
            joins(:courses, :course_categories).
            group("course_categories.id").
            order("course_categories.title")

Answer 1

我想通了，我需要將連接指定為字符串。