diff --git a/ccic-exam/src/main/resources/mappers/ExamScheduleMapper.xml b/ccic-exam/src/main/resources/mappers/ExamScheduleMapper.xml
index 36f06a8..738efef 100644
--- a/ccic-exam/src/main/resources/mappers/ExamScheduleMapper.xml
+++ b/ccic-exam/src/main/resources/mappers/ExamScheduleMapper.xml
@@ -50,7 +50,7 @@
     </select>
     <select id="getPaper" resultType="java.util.Map">
         select
-            id as paper_id,
+            id::text as paper_id,
             paper_name,
             total_score,
             exam_duration,