diff --git a/mailbox-lan/src/main/resources/mapper/DataMapper.xml b/mailbox-lan/src/main/resources/mapper/DataMapper.xml
index ecacc94..dbb1cdc 100644
--- a/mailbox-lan/src/main/resources/mapper/DataMapper.xml
+++ b/mailbox-lan/src/main/resources/mapper/DataMapper.xml
@@ -99,7 +99,7 @@ PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
 
         (
         select
-               CONCAT(COALESCE(ROUND(sum(COALESCE(b.resolved, 0))*100/SUM(CASE WHEN b.completed = '1' THEN 1 ELSE 0 END),0),0),'%') Rate,
+               CONCAT(COALESCE(ROUND(sum(COALESCE(b.resolved, 0))*100/NULLIF(SUM(CASE WHEN b.completed = '1' THEN 1 ELSE 0 END),0),0),0),'%') Rate,
         COALESCE(SUM(COALESCE(b.resolved, 0)),0)   resolved,COALESCE(SUM(CASE WHEN b.completed = '1' THEN 1 ELSE 0 END),0) rSum,
         count(b.mail_id) AS total2