一个客户有多个订单, 一个订单对应一个客户
需求:查询一个用户,得到对应的用户及相关订单
两个实体类
package com.itlike.domain;
import lombok.Getter;
import lombok.Setter;
import lombok.ToString;
import java.util.ArrayList;
import java.util.List;
@Setter@Getter@ToString
public class Customer {
private Integer cust_id;
private String cust_name;
private String cust_profession;
private String cust_phone;
private String email;
private List<Order> orders;
}
package com.itlike.domain;
import lombok.Getter;
import lombok.Setter;
import lombok.ToString;
@Setter@Getter@ToString
public class Order {
private Integer order_id;
private String order_name;
private String order_num;
}
customermapper.xml中的结果属性设置
级联一个对象的属性设置用association
级联多个对象的属性设置用collection
分步查询也用collection
javatype 表明orders是一个list集合 oftype表明list集合中装的都是 Order类型
<select id="getAllCustomers" resultMap="custMap">
SELECT * from `customer` as c LEFT JOIN `order` as o ON c.cust_id=o.cust_id;
</select>
<resultMap id="custMap" type="Customer">
<id column="cust_id" property="cust_id"/>
<result column="cust_name" property="cust_name"/>
<result column="cust_profession" property="cust_profession"/>
<result column="cust_phone" property="cust_phone"/>
<result column="email" property="email"/>
<collection property="orders" javaType="list" ofType="Order">
<id column="order_id" property="order_id"/>
<result column="order_num" property="order_num"/>
<result column="order_name" property="order_name"/>
</collection>
</resultMap>
和级联一个对象使用association相同,查询对象的自身属性不能省略!!!