肖海南查老师所教的学生方法修改

src/main/java/com/teaching/backend/service/impl/courses/CoursesServiceImpl.java

@@ -417,9 +417,11 @@ public class CoursesServiceImpl extends ServiceImpl<CoursesMapper, Courses> impl
                 List<StudentCourses> studentUsernames = studentCoursesMapper.selectBatchSomeStudent(courseId);
                 for (StudentCourses studentUsername : studentUsernames) {
                     UmsStudentManage umsStudentManage = umsStudentManageMapper.queryStudent(String.valueOf(studentUsername.getStudent()));
+                    if (umsStudentManage != null){
                         umsStudentManageList.add(umsStudentManage);
                     }
                 }
+            }
             return umsStudentManageList;
         }
         throw new BusinessException(400,"只有老师才有此功能");