mybatis连接数据库进行查询，返回对象为null

*Mapper.xml中代码

<select id="query" parameterType="int" resultType="User">
	select username , password from user where id=#{id}
</select>

主要测试代码

User user2 = userMapper.query(7);
System.out.println(user2);
System.out.println(user2.getName() + " " + user2.getPwd());

控制台输出user2为null,报错空指针异常

原因：实体类中属性(name, pwd)和表中字段(username, password)不一致导致
解决办法：关联实体类

<select id="query" parameterType="int" resultType="User">
	select username as name, password as pwd from user where id=#{id}
</select>