本文主要介绍了mybatis Plus 多表联合查询，分享给大家，具体如下：

//实体类package com.sk.skkill.entity;import com.baomidou.mybatisplus.annotation.TableField;import com.baomidou.mybatisplus.annotation.TableName;import lombok.Data;import java.io.Serializable;import java.util.Date;import java.util.List;@TableName("orders")@Datapublic class Order implements Serializable{ public static final long serialVersionUID =1L; private String id; private String orderName; private Date createTime; private Date updateTime; private String userID; @TableField(exist = false) private List<Users> listUsers; public Order(){ } public Order(String id, String orderName) { this.id = id; this.orderName = orderName; }}//dao层package com.sk.skkill.mapper;import com.baomidou.mybatisplus.core.mapper.BaseMapper;import com.baomidou.mybatisplus.extension.plugins.pagination.Page;import com.sk.skkill.entity.Order;import com.sun.javafx.collections.MappingChange;import org.apache.ibatis.annotations.Select;import java.util.List;import java.util.Map;public interface OrderMapper extends BaseMapper<Order>{List<Order> selectOrder();int addOrder(Order order);//多表联合查询 按条件orderID@Select("select t1.*,t2.user_name,t2.nick_name from orders t1 LEFT JOIN users t2 ON t1.user_id =t2.id WHERE t1.user_id= #{id}") List<Map<String,Object>> orderUserList(Page<Map<String,Object>> page,String id);}//service层package com.sk.skkill.service;import com.baomidou.mybatisplus.extension.plugins.pagination.Page;import com.baomidou.mybatisplus.extension.service.IService;import com.sk.skkill.entity.Order;import java.util.List;import java.util.Map;public interface OrderService extends IService<Order>{ List<Order> selectOrder(); int addOrder(Order order);// List<Map<String,Object>> orderUserList(Page<Map<String,Object>> page, String id); Page<Map<String,Object>> selectListPage(int current,int number,String id);}//serviceImpl层package com.sk.skkill.service.impl;import com.baomidou.mybatisplus.extension.plugins.pagination.Page;import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;import com.sk.skkill.entity.Order;import com.sk.skkill.mapper.OrderMapper;import com.sk.skkill.service.OrderService;import org.springframework.stereotype.Service;import java.util.List;import java.util.Map;@Servicepublic class OrderServiceImpl extends ServiceImpl<OrderMapper, Order> implements OrderService{ @Override public List<Order> selectOrder() { return baseMapper.selectList(null); } @Override public int addOrder(Order order) { return baseMapper.insert(order); } @Override public Page<Map<String, Object>> selectListPage(int current, int number,String id) { //新建分页 Page<Map<String,Object>> page =new Page<Map<String,Object>>(current,number); //返回结果 return page.setRecords(this.baseMapper.orderUserList(page,id)); }}//controller层 package com.sk.skkill.controller;import com.baomidou.mybatisplus.extension.plugins.pagination.Page;import com.sk.skkill.entity.Order;import com.sk.skkill.service.impl.OrderServiceImpl;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;import java.util.List;import java.util.Map;@RestController@RequestMapping("order")public class OrderController{ @Autowired private OrderServiceImpl service; @RequestMapping("selectOrder") public List<Order> selectOrder() { return service.selectOrder(); } @RequestMapping("addOrder") public int addOrder(Order order){ order=new Order("FGGG","蒙牛MILK"); return service.addOrder(order); } @RequestMapping("selectListPage") public List<Map<String,Object>> selectListPage(String id) { Page<Map<String, Object>> page = service.selectListPage(1, 2,id); return page.getRecords(); }}

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