Mybatis xml格式

下方这部分是必要的
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.cxy.cbms.manage.mapper.StaffMapper">
<select id="getAuthoritiesByRoleId" resultType="java.lang.String">
    SELECT r.name AS role_or_authority
    FROM staff_role sr
    INNER JOIN role r ON sr.role_id = r.id
    WHERE sr.user_id = #{staffId}

    UNION

    SELECT a.name AS role_or_authority
    FROM staff_role sr
    JOIN role_authority ra ON sr.role_id = ra.role_id
    JOIN authority a ON ra.authority_id = a.id
    WHERE sr.user_id = #{staffId};
</select>
</mapper>