case end 的用法

<select id="list" parameterType="com.gcsoft.pyas.bizModule.myTraining.dto.MyTrainingApplyDto" resultMap="BaseResultMap">
        SELECT * FROM (
          SELECT
            <![CDATA[
            CASE WHEN to_char(sysdate,'yyyy-mm-ddHH24:mi') >= (to_char(mytrain.TRAIN_START_DATE,'yyyy-mm-dd') || mytrain.TRAIN_START_TIME) AND
            to_char(sysdate,'yyyy-mm-ddHH24:mi') < (to_char(mytrain.TRAIN_END_DATE,'yyyy-mm-dd') || mytrain.TRAIN_END_TIME)
            THEN '4-2'
            WHEN to_char(sysdate,'yyyy-mm-ddHH24:mi') < (to_char(mytrain.TRAIN_START_DATE,'yyyy-mm-dd') || mytrain.TRAIN_START_TIME)
            THEN '4-1'
            WHEN to_char(sysdate,'yyyy-mm-ddHH24:mi') >= (to_char(mytrain.TRAIN_END_DATE,'yyyy-mm-dd') || mytrain.TRAIN_END_TIME)
            THEN '4-3'
            END AS TRAIN_STATUS,
            ]]>
            CASE WHEN tli.LEAVE_STATUS IS NULL THEN '-' ELSE tli.LEAVE_STATUS END AS LEAVE_STATUS,
            CASE WHEN ttoi.APPROVE_STATUS IS NULL THEN '未开始' ELSE ttoi.APPROVE_STATUS END AS OUTPUT_STATUS,
            --CASE WHEN ttoi.APPROVE_STATUS IS NULL THEN '-' ELSE '已评价' END AS EVALUATE_STATUS,
            <include refid="Base_Column_List"/>
          FROM (
            <![CDATA[
            SELECT tti.* FROM (SELECT * FROM TB_TRAINING_INFO WHERE TRAIN_STATUS = '4' AND DELETE_FLAG = '0') tti
            LEFT JOIN (SELECT BUS_ID, PARTICIPANT FROM TB_BUS_PARTICIPANTS_INFO WHERE BUS_TYPE = '0' and PARTICIPANT = #{currentUserName,jdbcType=CHAR} AND DELETE_FLAG = '0') tbpi on tbpi.BUS_ID = tti.ID
            LEFT JOIN (SELECT TRAIN_ID, ENROLLEE FROM TB_TRAINING_ENROLL_INFO WHERE ENROLLEE = #{currentUserName,jdbcType=CHAR} AND ENROLL_STATUS = '3' AND DELETE_FLAG = '0') tei on tei.TRAIN_ID = tti.ID
            WHERE (tti.TRAIN_PARTICIPANT_TYPE = '1' AND tti.NEED_ENROLL = '0')
              OR (tti.TRAIN_PARTICIPANT_TYPE = '1' AND tti.NEED_ENROLL <> '0' AND tei.ENROLLEE IS NOT NULL)
              OR (tti.TRAIN_PARTICIPANT_TYPE <> '1' AND tti.NEED_ENROLL = '0' AND tbpi.PARTICIPANT IS NOT NULL)
              OR (tti.TRAIN_PARTICIPANT_TYPE <> '1' AND tti.NEED_ENROLL <> '0' AND tei.ENROLLEE IS NOT NULL)
            ]]>
          ) mytrain
          LEFT JOIN (SELECT TRAIN_ID, LEAVE_STATUS FROM TB_TRAINING_LEAVE_INFO WHERE LEAVER = #{currentUserName,jdbcType=CHAR}) tli on tli.TRAIN_ID = mytrain.ID
          LEFT JOIN (SELECT TRAIN_ID, APPROVE_STATUS FROM TB_TRAINING_SUMMARY WHERE SUBMITTER = #{currentUserName,jdbcType=CHAR}) ttoi on ttoi.TRAIN_ID = mytrain.ID
        )
        <where>
          <if test="trainName != null and trainName != ''">
            and TRAIN_NAME LIKE concat(concat('%',#{trainName,jdbcType=OTHER}),'%')
          </if>
          <if test="trainStatus != null and trainStatus != ''">
            and TRAIN_STATUS = #{trainStatus, jdbcType=CHAR}
          </if>
          <if test="needEnroll != null and needEnroll != ''">
            and NEED_ENROLL = #{needEnroll, jdbcType=CHAR}
          </if>
        </where>
        order by case when TRAIN_STATUS = '4-2' then 1 when TRAIN_STATUS = '4-1' then 2 else 3 end, TRAIN_START_DATE
    </select>