List<Map<String, Object>> getPaperList(String dwmc);

<select id="getPaperList" resultType="java.util.Map">
    SELECT
    p.`id`,
    c.`company` companyName,
    p.`paper_num` paperNum,
    p.`paper_pwd` paperPwd,
    q.`test_name` testName
    FROM
    `t_paper` p
    JOIN `t_question_test` q
    ON p.`knowledge_test_id` = q.`id`
    JOIN company c
    ON q.`company_id` = c.`id`
    WHERE 1 = 1
    <if test="dwmc != null and dwmc !=''">
        AND c.company LIKE CONCAT('%',#{dwmc},'%')
    </if>
    order by p.id desc
</select>