mybatis文件映射之利用association进行关联查询（二）

与初探中大部分一样，只是修改resultMap中的相关信息。

    <resultMap type="com.gong.mybatis.bean.Employee" id="MySimpleMap2">
        <id column="id" property="id"/>
        <result column="last_name" property="lastName"/>
        <result column="gender" property="gender"/>
        <result column="email" property="email"/>
        <association property="dept" javaType="com.gong.mybatis.bean.Department">
            <id column="did" property="id"/>
            <result column="dept_name" property="deptName"/>
        </association>
    </resultMap>
    <select id="getEmpAndDept" resultMap="MySimpleMap2">
        SELECT e.id,e.last_name,e.gender,e.email,d.dept_name,d.id did 
        FROM tbl_employee e,tbl_department d
        WHERE e.d_id = d.id and e.id=#{id};
    </select>

说明：在resultMap中使用association标签，property属性对应着Employee中的成员属性的名称，javaType对应着该成员属性的类型，子标签id标识tbl_department中的主键，因为我们在select标签中将d.id取别名did，所以将did映射给Department中的id属性，然后通过result标签将普通的字段映射给Department中的deptName属性。

结果：

DEBUG 01-20 12:42:43,808 ==> Preparing: SELECT e.id,e.last_name,e.gender,e.email,d.dept_name,d.id did FROM tbl_employee e,tbl_department d WHERE e.d_id = d.id and e.id=?; (BaseJdbcLogger.java:145) DEBUG 01-20 12:42:43,887 ==> Parameters: 3(Integer) (BaseJdbcLogger.java:145) DEBUG 01-20 12:42:43,926 <== Total: 1 (BaseJdbcLogger.java:145) Employee [id=3, lastName=小红, gender=0, email=xiaohong@qq.com, dept=Department [id=1, deptName=开发部]] Department [id=1, deptName=开发部]

说明这种方法也是可以的。