class_course_id, class_id, course_id, course_type, create_time SELECT * FROM class_course as cc INNER JOIN course as c on cc.course_id = c.course_id c.is_valid = 1 AND class_id = #{classId} AND course_type = #{courseType} ORDER BY cc.class_course_id DESC SELECT FROM class_course WHERE class_id = #{classId} AND course_id = #{courseId} ORDER BY class_course_id DESC