mybatis 查询返回map集合

Map<String, CourseDto> allUserGroupCourseMap = courseService.getUserGroupCourseMapByUserIds(user.getId()+"");

/**
 * 获取用户小组课程信息 结果集map以 userId_CourseId 为key 以 CourseDto为value
 * @param userIds
 * @return
 */
public Map<String, CourseDto> getUserGroupCourseMapByUserIds(String userIds) {
    return sqlSession.selectMap("CourseMapper.getUserGroupCourseMapByUserIds",userIds,"userCourse");
}

<!--获取用户小组课程信息 结果集map以 userId_CourseId 为key 以 CourseDto为value-->
<select id="getUserGroupCourseMapByUserIds" parameterType="string" resultType="CourseDto">
    SELECT CONCAT_WS('_',edu_order_list_details.user_id,edu_course.id) AS userCourse,
        edu_course.id,
        edu_course.name,
        edu_course.exam_link AS examLink,
        edu_course.sell_type AS sellType,
        edu_course.discuss_number AS discussNumber,
        MIN(edu_order_list_details.pay_time) AS payTime
    FROM edu_course
    INNER JOIN edu_order_list_details ON edu_order_list_details.data_id = edu_course.id
    INNER JOIN edu_student_group ON edu_student_group.courseId = edu_course.id
    INNER JOIN edu_user_group ON edu_user_group.group_id = edu_student_group.id
    INNER JOIN user_user ON user_user.id = edu_user_group.user_id
    WHERE edu_order_list_details.pay_state = 'SUCCESS'
    and edu_order_list_details.user_id IN (${value})
    GROUP BY edu_order_list_details.user_id, edu_course.id
</select>