小班课添加学生，加入未开始的课程，加入班级群组

mec-biz/src/main/java/com/ym/mec/biz/service/impl/ClassGroupServiceImpl.java

@@ -605,6 +605,7 @@ public class ClassGroupServiceImpl extends BaseServiceImpl<Integer, ClassGroup>
         classGroupDao.addStudentNum(classGroup);
         //2、插入关联关系
         ClassGroupStudentMapper classGroupStudentMapper = new ClassGroupStudentMapper();
+        classGroupStudentMapper.setMusicGroupId(classGroup.getMusicGroupId());
         classGroupStudentMapper.setClassGroupId(classGroup.getId());
         classGroupStudentMapper.setUserId(userId);
         classGroupStudentMapper.setStatus(ClassGroupStudentStatusEnum.NORMAL);