Mybatis操作Oracle数据库：批量修改成功后返回的值是-1？

Mapper.xml

<update id="updateByMultiConditions" parameterType="java.util.List">   
    <foreach collection="list" item="item" index="index" open="begin" close="; end;" separator=";"> 
     update TB_DUTY 
     <set>
      <if test="item.morningPeopleIds != null and item.morningPeopleIds != '' " >
     MORNING_PEOPLE_IDS=#{item.morningPeopleIds,jdbcType=VARCHAR},
      </if>
      <if test="item.morningPeopleNames != null and item.morningPeopleNames != '' " >
     MORNING_PEOPLE_NAMES=#{item.morningPeopleNames,jdbcType=VARCHAR}, 
      </if> 
      <if test="item.afternoonPeopleIds != null and item.afternoonPeopleIds != '' " >
     AFTERNOON_PEOPLE_IDS=#{item.afternoonPeopleIds,jdbcType=VARCHAR},  
      </if>
      <if test="item.afternoonPeopleNames != null and item.afternoonPeopleNames != '' " >
     AFTERNOON_PEOPLE_NAMES=#{item.afternoonPeopleNames,jdbcType=VARCHAR}, 
      </if> 
      <if test="item.eveningPeopleIds != null and item.eveningPeopleIds != '' " >
     EVENING_PEOPLE_IDS=#{item.eveningPeopleIds,jdbcType=VARCHAR},  
      </if>
      <if test="item.eveningPeopleNames != null and item.eveningPeopleNames != '' " >
     EVENING_PEOPLE_NAMES=#{item.eveningPeopleNames,jdbcType=VARCHAR},
      </if>
      <if test="item.leaderIds != null and item.leaderIds != '' " >  
     LEADER_IDS=#{item.leaderIds,jdbcType=VARCHAR},  
      </if>
     <if test="item.leaderNames != null and item.leaderNames != '' " >
     LEADER_NAMES=#{item.leaderNames,jdbcType=VARCHAR},
     </if>
     </set> 
     where DUTY_ID=#{item.dutyId,jdbcType=INTEGER}
    </foreach>
</update>

Controller:

 int resultFlag=dutyService.updateByMultiConditions(dutyList2);

问题：

批量修改成功后返回的值是resultFlag=-1，作何解释？如何才能获得修改的行数？

遇到了同样的问题，返回-1好像就代表执行SQL成功

insert，返回值是：新插入行的主键（primary key）；需要包含语句，才会返回主键，否则返回值为null。
update/delete，返回值是：更新或删除的行数；无需指明resultClass；但如果有约束异常而删除失败，只能去捕捉异常。

insert返回的是插入的行数啊！如下图：

delete返回值是删除的行数没错，唯独update返回的不是修改的行数。**怎么才能得到修改的行数？我想知道这个。**
目前我的确是采用异常捕捉的方式来处理。

继续等待高手指教。。。。。。