第二阶段每日汇报20230517

一对多查询的语句
对应的sql语句：

select *,o.id oid from user u left join orders o on u.id=o.uid;

修改User实体
public class Order {

private int id;
private Date ordertime;
private double total;

//代表当前订单从属于哪一个客户
private User user;
}

public class User {

private int id;
private String username;
private String password;
private Date birthday;
//代表当前用户具备哪些订单
private List<Order> orderList;
}

创建UserMapper接口
public interface UserMapper {
List<User> findAll();
}

配置UserMapper.xml
<mapper namespace="com.zjq.mapper.UserMapper">
<resultMap id="userMap" type="com.zjq.domain.User">
<result column="id" property="id"></result>
<result column="username" property="username"></result>
<result column="password" property="password"></result>
<result column="birthday" property="birthday"></result>
<collection property="orderList" ofType="com.zjq.domain.Order">
<result column="oid" property="id"></result>
<result column="ordertime" property="ordertime"></result>
<result column="total" property="total"></result>
</collection>
</resultMap>
<select id="findAll" resultMap="userMap">
select *,o.id oid from user u left join orders o on u.id=o.uid
</select>
</mapper>

测试结果
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
List<User> all = mapper.findAll();
for(User user : all){
System.out.println(user.getUsername());
List<Order> orderList = user.getOrderList();
for(Order order : orderList){
System.out.println(order);
}
System.out.println("----------------------------------");
}

输出：