update

src/main/resources/mapper/StudentMapper.xml

@@ -769,6 +769,7 @@
                stu.exam_site,
                stu.exam_room
         from sc_student stu
+        left join sc_subject sb on sb.exam_id=stu.exam_id and sb.code=stu.subject_code
         where stu.exam_id = #{examId}
           and stu.subject_code = #{subjectCode}
           and stu.assigned = 1