Function: query a data list and each data contained in each data sub-sets
When you need to query more than 1 order data and order data at the same time you need to be included in the order details data: usage scenarios.
2. When you need to query the data and commenting on the comment data needs to include data Comments Reply
Functional effects Overview Figure:
1. Dao layer defines
package com.ljw.dao; import java.util.List; amount com.ljw.vo.Order; public interface OrderMapper { List<Order> findAllOrder(); }
2. Mybatis Configuration
<!-- 实体类映射 --> <resultMap type="cn.ljw.vo.Order" id="OrderMap"> <id column="order_id" jdbcType="INTEGER" property="orderId" /> <result column="order_number" jdbcType="VARCHAR" property="orderNumber" /> <result column="order_time" jdbcType="TIMESTAMP" property="orderTime" /> <collection property="orderDetails" ofType="cn.ljw.vo.OrderDetail" javaType="java.util.List"> <id column="detail_order_detail_id" jdbcType="INTEGER" property="orderDetailId" /> <result column="detail_order_id" jdbcType="INTEGER" property="orderId" /> <result column="detail_commodity_name" jdbcType="VARCHAR" property="commodityName" /> <result column="detail_commodity_number" jdbcType="INTEGER" property="commodityNumber" /> </collection> </resultMap> <-! Query code -> < the SELECT the above mentioned id = "findAllOrder" resultMap = "OrderMap" > SELECT order.order_id, order.order_number, order.order_time, order_detail.order_detail_id AS detail_order_detail_id, order_detail.order_id AS detail_order_id, order_detail.commodity_name AS detail_commodity_name, order_detail.commodity_number AS detail_commodity_number FROM order LEFT JOIN order_detail ON order.order_id = order_detail.order_id </select>
3. po entity class definitions
/** * Orders table */ public class Order implements Serializable { /** * Order ID */ private Integer orderId; /** * Order Number */ private String orderNumber; /** * Order Time */ private Date orderTime; /** * Order Details collections */ private List<OrderDetail> orderDetails; public Integer getOrderId() { return orderId; } public void setOrderId(Integer orderId) { this.orderId = orderId; } public String getOrderNumber() { return orderNumber; } public void setOrderNumber(String orderNumber) { this.orderNumber = orderNumber; } public Date getOrderTime() { return orderTime; } public void setOrderTime(Date orderTime) { this.orderTime = orderTime; } public List<OrderDetail> getOrderDetails() { return orderDetails; } public void setOrderDetails(List<OrderDetail> orderDetails) { this.orderDetails = orderDetails; } }
/** * Order Details */ public class OrderDetail implements Serializable { /** * Order Details ID */ private Integer orderDetailId; /** * Order ID */ private Integer orderId; /** * product name */ private String commodityName; /** * Number of Products */ private Integer commodityNumber; public Integer getOrderDetailId() { return orderDetailId; } public void setOrderDetailId(Integer orderDetailId) { this.orderDetailId = orderDetailId; } public Integer getOrderId() { return orderId; } public void setOrderId(Integer orderId) { this.orderId = orderId; } public String getCommodityName() { return commodityName; } public void setCommodityName(String commodityName) { this.commodityName = commodityName; } public Integer getCommodityNumber() { return commodityNumber; } public void setCommodityNumber(Integer commodityNumber) { this.commodityNumber = commodityNumber; } }