group by问题 和 剧集为空的问题

src/main/resources/mapper/course/CourseCollectDao.xml

@@ -49,6 +49,7 @@
         FROM `course_collect` c1
         WHERE c1.classify = 3
           AND c1.user_id = #{userId}
+        group by c1.course_id
         order by c1.create_time desc
     </select>
 </mapper>