mapper simple file format

<?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="包名">

<select id="接口方法名" resultType=model地址">
select id , title ,detail_desc , answer_count,last_modified
from questions order by last_modified desc
</select>