mybatis 一对一 一对多

数据库多表一对一查询

 <!--定义封装account和user-->
    <resultMap id="accountUserMap" type="account">
      <!--account的属性,id代表其主键，result为其他属性-->
        <id column="aid" property="id"></id>
        <result property="uid" column="uid"></result>
        <result property="money" column="money"></result>
        <!--一对一,property是account的一个属性，user，类型为user类-->
        <association property="user" column="uid" javaType="user">
            <id column="id" property="id"></id>
            <result column="username" property="username"></result>
            <result column="address" property="address"></result>
            <result column="sex" property="sex"></result>
            <result column="birthday" property="birthday"></result>
        </association>
    </resultMap>

一对多

 <!--定义封装account和user-->
    <resultMap id="RoleUserMap" type="role">
      <!--account的属性,id代表其主键，result为其他属性-->
        <id column="rid" property="id"></id>
        <result property="roleName" column="role_name"></result>
        <result property="roleDesc" column="role_desc"></result>
        <!--这是使用collection集合，oftype为封装到javaBean类,也就是尖括号的泛型private List<Post>posts-->
        <collection property="users" ofType="user">
            <id column="id" property="id"></id>
            <result column="username" property="username"></result>
            <result column="address" property="address"></result>
            <result column="sex" property="sex"></result>
            <result column="birthday" property="birthday"></result>
        </collection>
    </resultMap>