准备如下用户表，订单表，订单明细表，商品表

用户表：user_id,user_name

订单表：order_id,order_no,user_id

订单明细表：orderdetail_id,order_id,product_id

商品表：product_id,product_name

 

实体类

package com.zns.domain;import java.util.List;public class User {    private int userid;    private String username;    private List
     
       orders;    public int getUserid() {        return userid;    }    public void setUserid(int userid) {        this.userid = userid;    }    public String getUsername() {        return username;    }    public void setUsername(String username) {        this.username = username;    }    public List
      
        getOrders() {        return orders;    }    public void setOrders(List
       
         orders) {        this.orders = orders;    }    @Override    public String toString() {        return "User [userid=" + userid + ", username=" + username + ", orders=" + orders + "]";    }}
       
      
     

 

package com.zns.domain;import java.util.List;public class Order {    private int orderid;    private String orderno;    private int userid;    private User user;    private List
     
       orderDetails;    public int getOrderid() {        return orderid;    }    public void setOrderid(int orderid) {        this.orderid = orderid;    }    public String getOrderno() {        return orderno;    }    public void setOrderno(String orderno) {        this.orderno = orderno;    }    public int getUserid() {        return userid;    }    public void setUserid(int userid) {        this.userid = userid;    }    public User getUser() {        return user;    }    public void setUser(User user) {        this.user = user;    }    public List
      
        getOrderDetails() {        return orderDetails;    }    public void setOrderDetails(List
       
         orderDetails) {        this.orderDetails = orderDetails;    }    @Override    public String toString() {        return "Order [orderid=" + orderid + ", orderno=" + orderno + ", userid=" + userid + ", user=" + user                + ", orderDetails=" + orderDetails + "]";    }}
       
      
     

 

package com.zns.domain;public class OrderDetail {    private int orderdetailid;    private int orderid;    private int productid;    private Product product;    public int getOrderdetailid() {        return orderdetailid;    }    public void setOrderdetailid(int orderdetailid) {        this.orderdetailid = orderdetailid;    }    public int getOrderid() {        return orderid;    }    public void setOrderid(int orderid) {        this.orderid = orderid;    }    public int getProductid() {        return productid;    }    public void setProductid(int productid) {        this.productid = productid;    }    public Product getProduct() {        return product;    }    public void setProduct(Product product) {        this.product = product;    }    @Override    public String toString() {        return "OrderDetail [orderdetailid=" + orderdetailid + ", orderid=" + orderid + ", productid=" + productid                + ", product=" + product + "]";    }}

 

package com.zns.domain;public class Product {    private int productid;    private String productname;    public int getProductid() {        return productid;    }    public void setProductid(int productid) {        this.productid = productid;    }    public String getProductname() {        return productname;    }    public void setProductname(String productname) {        this.productname = productname;    }    @Override    public String toString() {        return "Product [productid=" + productid + ", productname=" + productname + "]";    }}

 

 

Mybatis映射配置如下

                 SELECT        a.order_id,        a.order_no,        b.user_name        FROM        tb_order AS a,        tb_user AS b        WHERE        a.user_id = b.user_id        
             
              
              
              
                  
                   
               
          
         
                 SELECT        a.order_id,        a.order_no,        b.user_name,        c.orderdetail_id,        c.product_id        FROM        tb_order AS a,        tb_user AS b,        tb_order_detail AS c        WHERE        a.user_id = b.user_id        AND a.order_id = c.order_id        
             
              
              
              
                  
                   
               
              
                  
                   
                   
               
          
         
                 SELECT        a.user_id,        a.user_name,        b.order_id,        b.order_no,        c.orderdetail_id,        c.product_id,        d.product_name        FROM        tb_user AS a,        tb_order AS b,        tb_order_detail AS c,        tb_product AS d        WHERE        a.user_id = b.user_id        AND b.order_id = c.order_id        AND c.product_id = d.product_id