修复修改班级学生

suser/src/main/java/com/xhkjedu/suser/service/gradeclass/ClassStudentService.java

         }
         String examno = model.getExamno();
         if (N_Utils.isNotEmpty(examno)) {
-            TSchool school = schoolMapper.getSchoolInfoById(model.getSchoolid());
+            TSchool school = schoolMapper.getSchoolInfoById(u.getSchoolid());
             Integer limitenolen = school.getLimitenolen();
             if (!N_Utils.isEmptyInteger(limitenolen) && !limitenolen.equals(examno.length())) {
                 return new ResultVo(1, "准考证号长度不符合要求");