mybaties将时间格式成字符串

有时候在做根据年月查询时要用到对时间切割字符串，代码如下：

select  of.id,  of.name,    (select count(ctd.id) from car_train_driver ctd where ctd.done= '1' and ctd.car_train_id in     (select id from car_train where parent_id in      (select id from car_train where user_id in       (select id from sys_user where office_id in        (select id from  sys_office where parent_id in         (select id from  sys_office where parent_id = of.id         <if test="year !=null and year !=''">            AND DATE_FORMAT(ctd.create_date,"%Y")= #{year}         </if>         <if test="month != null and month !=''">            AND DATE_FORMAT(ctd.create_date,"%m")=#{month}         </if>         )        )       )      )     )    ) num,        format(if((select (sum(score)/(count(id)*5))*100*          (select count(ctd.id) from car_train_driver ctd where ctd.done= '1' and ctd.car_train_id in          (select id from car_train where parent_id in           (select id from car_train where user_id in            (select id from sys_user where office_id in            (select id from  sys_office where parent_id in             (select id from  sys_office where parent_id = of.id           <if test="year !=null and year !=''">              AND DATE_FORMAT(ctd.create_date,"%Y")= #{year}           </if>             <if test="month != null and month !=''">              AND DATE_FORMAT(ctd.create_date,"%m")=#{month}           </if>             )             )            )           )          )         )         from car_configuration_train where car_train_driver_id in         (select id from car_train_driver where done= '1' and car_train_id in          (select id from car_train where parent_id in           (select id from car_train where user_id in            (select id from sys_user where office_id in            (select id from  sys_office where parent_id in             (select id from  sys_office where parent_id = of.id)             )            )           )          )         )        ) is null,0,(select (sum(score)/(count(id)*5))*100*          (select count(ctd.id) from car_train_driver ctd where ctd.done= '1' and ctd.car_train_id in          (select id from car_train where parent_id in           (select id from car_train where user_id in            (select id from sys_user where office_id in            (select id from  sys_office where parent_id in             (select id from  sys_office where parent_id = of.id            <if test="year !=null and year !=''">               AND DATE_FORMAT(ctd.create_date,"%Y")= #{year}            </if>            <if test="month != null and month !=''">               AND DATE_FORMAT(ctd.create_date,"%m")=#{month}            </if>            )             )            )           )          )         )         from car_configuration_train where car_train_driver_id in         (select id from car_train_driver where done= '1' and car_train_id in          (select id from car_train where parent_id in           (select id from car_train where user_id in            (select id from sys_user where office_id in            (select id from  sys_office where parent_id in             (select id from  sys_office where parent_id = of.id)             )            )           )          )         )        )),0) score  from   <choose>      <when test="user.id != null and user.id != ''">         (select id,name from  sys_office where  parent_id = '1') of      </when>      <otherwise>         (select id,name from  sys_office where parent_id =         (select parent_id from  sys_office where id = #{user.office.id})         ) of      </otherwise>   </choose>  ORDER BY num desc;以上红色字体是关键代码，返回的类型是hashmap.