1、提交作业添加限制；

2、服务指标；

mec-biz/src/main/resources/config/mybatis/StudentMapper.xml

@@ -182,7 +182,7 @@
         <if test="studentId!=null">
             user_id_ = #{studentId}
         </if>
-        <if test="studentIds.size()>0">
+        <if test="studentIds!=null and studentIds.size()>0">
             user_id_ IN
             <foreach collection="studentIds" item="studentId" open="(" close=")" separator=",">
                 #{studentId}