resultMap 映射

1. sql的重用：定义一个sql片段，可在任何SQL语句中重用该片段。

"personColumns"> name, sex, updateTime
"selectPerson" parameterType="int" resultType="hashmap">
    select id, "personColumns"/> from person where id =#{id};

2. javabean别名：不用每次写包路径

int” resultType=”User”>
    select id, username, hashedPassword from some_table where id = #{id}

3. 表与实体列名不匹配的解决

a) SQL的别名

int” resultType=”User”>
select user_id as "id", user_name as userName, hashed_password as hashedPassword from some_table where id = #{id}

b)定义外部的resultMap

"userResult" type="User">
    "id" column="_id" />
    "name" column="_name" />
    "password" column="_password" />


"selectUser" parameterType="int" resultMap="userResult">
    select _id, _name, _password from _user where _id =#{id};

转载于:https://www.cnblogs.com/AutumnRhyme/p/5614030.html