text: <?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.md.demo.vo.CityVo">
  
  	<select id="listCities" resultType="com.md.demo.vo.CityVo">
  		select * from city
  	</select>
  	
  	<select id="getCityById" resultType="com.md.demo.vo.CityVo">
  		select * from city where id = #{id}
  	</select>
  
  </mapper>