Mybatis多层嵌套查询
三张表：user article blog
表的存储sql文件
/*
Navicat MySQL Data Transfer
Source Server : localhost
Source Server Version : 50620
Source Host : localhost:3306
Source Database : mybatis
Target Server Type : MYSQL
Target Server Version : 50620
File Encoding : 65001
Date: 2014-10-19 18:27:31
*/
SET FOREIGN_KEY_CHECKS=0;
-- ----------------------------
-- Table structure for `user`
-- ----------------------------
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`userName` varchar(50) DEFAULT NULL,
`userAge` int(11) DEFAULT NULL,
`userAddress` varchar(200) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of user
-- ----------------------------
INSERT INTO `user` VALUES ('1', 'summer', '30', 'shanghai');
INSERT INTO `user` VALUES ('2', 'test1', '22', 'suzhou');
INSERT INTO `user` VALUES ('3', 'test1', '29', 'some place');
INSERT INTO `user` VALUES ('4', 'lu', '28', 'some place');
INSERT INTO `user` VALUES ('5', 'xiaoxun', '27', 'nanjing');
-- ----------------------------
-- Table structure for `article`
-- ----------------------------
DROP TABLE IF EXISTS `article`;
CREATE TABLE `article` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`userid` int(11) NOT NULL,
`title` varchar(100) DEFAULT NULL,
`content` text,
`blogid` int(11) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of article
-- ----------------------------
INSERT INTO `article` VALUES ('1', '1', 'test_title_1', 'test_content_1', '1');
INSERT INTO `article` VALUES ('2', '1', 'test_title_2', 'test_content_2', '1');
INSERT INTO `article` VALUES ('3', '1', 'test_title_3', 'test_content_3', '2');
INSERT INTO `article` VALUES ('4', '1', 'test_title_4', 'test_content_4', '2');
INSERT INTO `article` VALUES ('5', '2', 'test_title_5', 'test_content_5', '2');
-- ----------------------------
-- Table structure for `blog`
-- ----------------------------
DROP TABLE IF EXISTS `blog`;
CREATE TABLE `blog` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`title` varchar(200) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of blog
-- ----------------------------
INSERT INTO `blog` VALUES ('1', 'xiaoxun_blog');
INSERT INTO `blog` VALUES ('2', 'zhang_blog');
实体类
package com.mybatis.test;
public class Article {
private int id;
private User user;
private String title;
private String content;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
}
package com.mybatis.test;
import java.util.List;
public class Blog {
private int id;
private String title;
private List articles;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public List getArticles() {
return articles;
}
public void setArticles(List articles) {
this.articles = articles;
}
}
XML
Mybatis多层嵌套查询(多对多)
依赖
com.baomidou mybatis-plus-boot-starter 3.4.3
实体类Setmeal
@Data
@TableName("t_setmeal")
public class Setmeal implements Serializable {
@TableId(type = IdType.AUTO)
private Integer id;
private String name;
private String code;
private String helpCode;
private String sex;//套餐适用性别：0不限 1男 2女
private String age;//套餐适用年龄
private Float price;//套餐价格
private String remark;
private String attention;
private String img;//套餐对应图片存储路径
@TableField(exist = false)
private List checkGroups;//体检套餐对应的检查组，多对多关系
}
实体类CheckGroup
@Data
@TableName("t_checkgroup")
public class CheckGroup {
@TableId(type = IdType.AUTO)
private Integer id;//主键
private String code;//编码
private String name;//名称
private String helpCode;//助记
private String sex;//适用性别
private String remark;//介绍
private String attention;//注意事项
@TableField(exist = false)
private List checkItems;//一个检查组合包含多个检查项
}
实体类CheckItem
@Data
@TableName("t_checkitem")
public class CheckItem {
@TableId(type = IdType.AUTO)
private Integer id;//主键
private String code;//项目编码
private String name;//项目名称
private String sex;//适用性别
private String age;//适用年龄（范围），例如：20-50
private Float price;//价格
private String type;//检查项类型，分为检查和检验两种类型
private String remark;//项目说明
private String attention;//注意事项
}
中间表t_setmeal_checkgroup
中间表t_checkgroup_checkitem
可以看出Setmeal里面包含多个CheckGroup，而CheckGroup包括多个CheckItem
mapper层
CheckItemMapper /** * 根据检查组得到检查项 * @param checkgroupId * @return */ ListfindCheckItemById(@Param("checkgroupId") Integer checkgroupId);
CheckItemMapper.xml
CheckGroupMapper
/** * 根据体验套餐的id得到检查项的分组 * @param setmealId * @return */ ListfindCheckGroupBySetmealId(@Param("setmealId") Integer setmealId);
CheckGroupMapper.xml
column="id"应该是把CheckGroup的id当作参数传给findCheckGroupBySetmealId
SetmealMapper
/**
* 根据id查询套餐信息
* @param id
* @return
*/
Setmeal findById(@Param("id") int id);
SetmealMapper.xml
测试
一个setmeal里面有多个checkGroup，checkGroup里面有多个checkItems
以上为个人经验，希望能给大家一个参考，也希望大家多多支持脚本之家。