mybatis Plus 多表联合查询的实现示例_JAVA教程

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

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									//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")

									@Data

									public 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;

									  }

									}

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									//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);

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									//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);

									}

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									//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);

									}

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									//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;

									@Service

									public 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));

									  }

									}

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									//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();

									  }

									}