diff --git a/bonus-modules/bonus-exam/src/main/resources/mapper/exam/StudentManagementMapper.xml b/bonus-modules/bonus-exam/src/main/resources/mapper/exam/StudentManagementMapper.xml
index 6552a2a..1c1f0e9 100644
--- a/bonus-modules/bonus-exam/src/main/resources/mapper/exam/StudentManagementMapper.xml
+++ b/bonus-modules/bonus-exam/src/main/resources/mapper/exam/StudentManagementMapper.xml
@@ -253,10 +253,10 @@
             and etu.pro_id = #{proId}
         </if>
         <if test="type == '1' or type == 1">
-            and etu.sign_time is not null and etu.sign_time != '' and etu.sign_time != 'null'
+            and etu.sign_time is not null
         </if>
         <if test="type == '2' or type == 2">
-            and (etu.sign_time is null or etu.sign_time = '' or etu.sign_time = 'null')
+            AND etu.sign_time IS NULL
         </if>
     </select>
     <select id="getExamCount" resultType="java.lang.Integer">
diff --git a/bonus-modules/bonus-flowable/src/main/java/com/bonus/flowable/listener/MultiInstanceCompleteTask.java b/bonus-modules/bonus-flowable/src/main/java/com/bonus/flowable/listener/MultiInstanceCompleteTask.java
index ba4fc7b..f1e500a 100644
--- a/bonus-modules/bonus-flowable/src/main/java/com/bonus/flowable/listener/MultiInstanceCompleteTask.java
+++ b/bonus-modules/bonus-flowable/src/main/java/com/bonus/flowable/listener/MultiInstanceCompleteTask.java
@@ -1,7 +1,6 @@
 package com.bonus.flowable.listener;
 
 import com.bonus.flowable.service.BusinessService;
-import com.sun.javafx.collections.MappingChange;
 import org.flowable.bpmn.model.ExtensionAttribute;
 import org.flowable.bpmn.model.FlowElement;
 import org.flowable.bpmn.model.UserTask;