Mybatis映射文件起别名

Question

 <select id="selectAll" resultType="com.pojo.User">
        select id,user_name as username,password from tb_user;
    </select>

实体类的属性名为user_name，字段名为username，在SQL映射文件这里我起别名"user_name as username"，为什么还会显示Unknown column 'user_name' in 'field list'?

Answer 1

SQL写错了，应该是usrrname as user_name啊