因为两次都错在这个上面上，所以还是记录一下。。。。

resultType是直接表示返回类型的，比如Integer,String, List<Integer>也是一样，resultMap则是对外部ResultMap的引用

例如：

  <select id="selectByStatus" resultType="java.lang.Integer" parameterType="com.meihui.learning.viewmodel.admin.question.QuestionStatusVM">
    SELECT
    t_question.id
    FROM t_question LEFT JOIN t_question_status on t_question_status.question_id = t_question.id
    <where>
      and t_question.deleted = 0
      <if test="questionType != null">
        and t_question.question_type = #{questionType}
      </if>
      <if test="wrongStatus != null ">
        and t_question_status.wrong_status= #{wrongStatus}
      </if>
      <if test="subjectSecondId != null ">
        and t_question.subject_second_id= #{subjectSecondId}
      </if>
      <if test="subjectId != null ">
        and t_question.subject_id= #{subjectId}
      </if>
    </where>
  </select>

  <select id="getUserDingTaskByDdUserIdDeptId" resultMap="BaseResultMap">
    select
    <include refid="Base_Column_List"/>
    from t_user_ding_task
    where dd_user_id = #{ddUserId} and dept_id = #{deptId} and deleted = 0 limit 1
  </select>

 还有一种略特殊的，其实也不算特殊，之前没理解清楚，下面并没有引用外部的，所以用resultType是正常的。。 <include refid="Base_Column_List"/>这种才是外部引用。。。

  <select id="selectCountByDate"  resultType="com.meihui.learning.domain.other.KeyValue">
		SELECT create_time as name,COUNT(create_time) as value from
		        (
				  SELECT DATE_FORMAT(create_time,'%Y-%m-%d') as create_time from 
                   t_user_event_log
					WHERE  create_time  between  #{startTime}  and  #{endTime}
				) a
		GROUP BY create_time
  </select>

    List<KeyValue> selectCountByDate(@Param("startTime") Date startTime, @Param("endTime") Date endTime);

https://blog.csdn.net/woshixuye/article/details/27521071  这位很详细

还有就是关于传递参数为list的时候的一个小问题。。

默认的list，亲测可行

    List<UserDTO> selectByDdUserIds(List<String> list);

  <select id="selectByDdUserIds" resultMap="BaseResultMap">
    select
    <include refid="Base_Column_List" />
    from t_user_ding
    where id in
    <foreach item="ddUserId" collection="list" open="(" separator=","
             close=")">
      #{ddUserId}
    </foreach>
  </select>

这里的collection为list，所以上面的代码里不用传@Param("list")之类的

但是如果是自定义的，就得加上@Param("ddUserIds")之类的。。

    List<UserDTO> selectByDdUserIds(@Param("ddIdList") List<String> ddIdList);

  <select id="selectByDdUserIds" resultMap="BaseResultMap">
    select
    <include refid="Base_Column_List" />
    from t_user_ding
    where id in
    <foreach item="ddUserId" collection="ddIdList" open="(" separator=","
             close=")">
      #{ddUserId}
    </foreach>
  </select>

但其实我代码里这么写还是报错 。。。清过redis缓存，clean也clean过了。。就是报错。。。但是其他的xml里的也是这写法就可以，应该还是哪里出问题了。。

https://blog.csdn.net/qq_28379809/article/details/83342196 这位也很详细。。