Mybatis级联查询(多对一、一对多)Demo及问题

Mybatis级联查询(多对一、一对多)Demo及问题

  • 1、问题描述
  • 2、工程源码
    • A、首先是数据库部分
    • B、工程代码
  • 3、问题解决
  • 4、总结

1、问题描述

今天做数据报表的时候,不想使用java代码做各种组合了,直接在MySQL里面搞级联查询,但是遇到了很多问题,在这里记录一下,防止后来的人踩坑。首先搭建一下环境,如果有人想学习,也可以直接拷贝代码运行即可。

2、工程源码

A、首先是数据库部分

sql

create database mango;
use mango;
CREATE TABLE `sys_role` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT '编号',
  `name` varchar(100) DEFAULT NULL COMMENT '角色名称',
  `remark` varchar(100) DEFAULT NULL COMMENT '备注',
  `create_by` varchar(50) DEFAULT NULL COMMENT '创建人',
  `create_time` datetime DEFAULT NULL COMMENT '创建时间',
  `last_update_by` varchar(50) DEFAULT NULL COMMENT '更新人',
  `last_update_time` datetime DEFAULT NULL COMMENT '更新时间',
  `del_flag` tinyint(4) DEFAULT '0' COMMENT '是否删除  -1:已删除  0:正常',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8 COMMENT='角色管理'

CREATE TABLE `sys_user` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT '编号',
  `name` varchar(50) NOT NULL COMMENT '用户名',
  `nick_name` varchar(150) DEFAULT NULL COMMENT '昵称',
  `avatar` varchar(150) DEFAULT NULL COMMENT '头像',
  `password` varchar(100) DEFAULT NULL COMMENT '密码',
  `salt` varchar(40) DEFAULT NULL COMMENT '加密盐',
  `email` varchar(100) DEFAULT NULL COMMENT '邮箱',
  `mobile` varchar(100) DEFAULT NULL COMMENT '手机号',
  `status` tinyint(4) DEFAULT NULL COMMENT '状态  0:禁用   1:正常',
  `dept_id` bigint(20) DEFAULT NULL COMMENT '机构ID',
  `create_by` varchar(50) DEFAULT NULL COMMENT '创建人',
  `create_time` datetime DEFAULT NULL COMMENT '创建时间',
  `last_update_by` varchar(50) DEFAULT NULL COMMENT '更新人',
  `last_update_time` datetime DEFAULT NULL COMMENT '更新时间',
  `del_flag` tinyint(4) DEFAULT '0' COMMENT '是否删除  -1:已删除  0:正常',
  PRIMARY KEY (`id`),
  UNIQUE KEY `name` (`name`)
) ENGINE=InnoDB AUTO_INCREMENT=40 DEFAULT CHARSET=utf8 COMMENT='用户管理'

CREATE TABLE `sys_user_role` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT '编号',
  `user_id` bigint(20) DEFAULT NULL COMMENT '用户ID',
  `role_id` bigint(20) DEFAULT NULL COMMENT '角色ID',
  `create_by` varchar(50) DEFAULT NULL COMMENT '创建人',
  `create_time` datetime DEFAULT NULL COMMENT '创建时间',
  `last_update_by` varchar(50) DEFAULT NULL COMMENT '更新人',
  `last_update_time` datetime DEFAULT NULL COMMENT '更新时间',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=90 DEFAULT CHARSET=utf8 COMMENT='用户角色'

CREATE TABLE `sys_dept` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT '编号',
  `name` varchar(50) DEFAULT NULL COMMENT '机构名称',
  `parent_id` bigint(20) DEFAULT NULL COMMENT '上级机构ID,一级机构为0',
  `order_num` int(11) DEFAULT NULL COMMENT '排序',
  `create_by` varchar(50) DEFAULT NULL COMMENT '创建人',
  `create_time` datetime DEFAULT NULL COMMENT '创建时间',
  `last_update_by` varchar(50) DEFAULT NULL COMMENT '更新人',
  `last_update_time` datetime DEFAULT NULL COMMENT '更新时间',
  `del_flag` tinyint(4) DEFAULT '0' COMMENT '是否删除  -1:已删除  0:正常',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=15 DEFAULT CHARSET=utf8 COMMENT='机构管理'



INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (1, 1, 1, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (2, 2, 1, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (26, 5, 3, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (33, 6, 2, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (34, 4, 2, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (35, 9, 2, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (36, 10, 3, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (37, 11, 2, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (38, 12, 3, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (39, 15, 2, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (41, 16, 3, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (42, 8, 2, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (43, 7, 4, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (45, 18, 2, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (46, 17, 3, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (47, 3, 4, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (48, 21, 2, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (57, 31, 2, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (58, 30, 2, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (59, 32, 3, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (73, 33, 8, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (74, 25, 8, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (75, 25, 2, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (80, 22, 2, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (81, 23, 3, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (82, 24, 4, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (83, 26, 3, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (85, 29, 2, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (86, 28, 4, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (87, 27, 3, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (88, 39, 4, NULL, NULL, NULL, NULL);
INSERT INTO `sys_user_role`(`id`, `user_id`, `role_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`) VALUES (89, 39, 3, NULL, NULL, NULL, NULL);

INSERT INTO `sys_role`(`id`, `name`, `remark`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (1, 'admin', '超级管理员', 'admin', '2019-01-19 11:11:11', 'admin', '2019-01-19 19:07:18', 0);
INSERT INTO `sys_role`(`id`, `name`, `remark`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (2, 'mng', '项目经理', 'admin', '2019-01-19 11:11:11', 'admin', '2019-01-19 11:39:28', 0);
INSERT INTO `sys_role`(`id`, `name`, `remark`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (3, 'chenwei', '陈伟', 'admin', '2020-05-07 15:52:53', 'admin', '2020-05-07 15:52:59', 0);
INSERT INTO `sys_role`(`id`, `name`, `remark`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (4, 'test', '测试人员', 'admin', '2019-01-19 11:11:11', 'admin', '2019-01-19 11:11:11', 0);

INSERT INTO `sys_dept`(`id`, `name`, `parent_id`, `order_num`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (1, '轻尘集团', NULL, 0, 'admin', '2018-09-23 19:35:22', NULL, NULL, 0);
INSERT INTO `sys_dept`(`id`, `name`, `parent_id`, `order_num`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (2, '牧尘集团', NULL, 1, 'admin', '2018-09-23 19:35:55', NULL, NULL, 0);
INSERT INTO `sys_dept`(`id`, `name`, `parent_id`, `order_num`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (3, '三国集团', NULL, 2, 'admin', '2018-09-23 19:36:24', NULL, NULL, 0);
INSERT INTO `sys_dept`(`id`, `name`, `parent_id`, `order_num`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (4, '上海分公司', 2, 0, 'admin', '2018-09-23 19:37:03', NULL, NULL, 0);
INSERT INTO `sys_dept`(`id`, `name`, `parent_id`, `order_num`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (5, '北京分公司', 1, 1, 'admin', '2018-09-23 19:37:17', NULL, NULL, 0);
INSERT INTO `sys_dept`(`id`, `name`, `parent_id`, `order_num`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (6, '北京分公司', 2, 1, 'admin', '2018-09-23 19:37:28', NULL, NULL, 0);
INSERT INTO `sys_dept`(`id`, `name`, `parent_id`, `order_num`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (7, '技术部', 5, 0, 'admin', '2018-09-23 19:38:00', NULL, NULL, 0);
INSERT INTO `sys_dept`(`id`, `name`, `parent_id`, `order_num`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (8, '技术部', 4, 0, 'admin', '2018-09-23 19:38:10', NULL, NULL, 0);
INSERT INTO `sys_dept`(`id`, `name`, `parent_id`, `order_num`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (9, '技术部', 6, 0, 'admin', '2018-09-23 19:38:17', NULL, NULL, 0);
INSERT INTO `sys_dept`(`id`, `name`, `parent_id`, `order_num`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (10, '市场部', 5, 0, 'admin', '2018-09-23 19:38:45', NULL, NULL, 0);
INSERT INTO `sys_dept`(`id`, `name`, `parent_id`, `order_num`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (11, '市场部', 6, 0, 'admin', '2018-09-23 19:39:01', NULL, NULL, 0);
INSERT INTO `sys_dept`(`id`, `name`, `parent_id`, `order_num`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (12, '魏国', 3, 0, 'admin', '2018-09-23 19:40:42', NULL, NULL, 0);
INSERT INTO `sys_dept`(`id`, `name`, `parent_id`, `order_num`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (13, '蜀国', 3, 1, 'admin', '2018-09-23 19:40:54', NULL, NULL, 0);
INSERT INTO `sys_dept`(`id`, `name`, `parent_id`, `order_num`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (14, '吴国', 3, 2, 'admin', '2018-09-23 19:41:04', NULL, NULL, 0);


INSERT INTO `sys_user`(`id`, `name`, `nick_name`, `avatar`, `password`, `salt`, `email`, `mobile`, `status`, `dept_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (1, 'admin', '字节跳动万岁', NULL, 'bd1718f058d8a02468134432b8656a86', 'YzcmCZNvbXocrsz9dm8e', '[email protected]', '13612345678', 1, 4, 'admin', '2018-08-14 11:11:11', 'admin', '2018-08-14 11:11:11', 0);
INSERT INTO `sys_user`(`id`, `name`, `nick_name`, `avatar`, `password`, `salt`, `email`, `mobile`, `status`, `dept_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (22, 'liubei', '刘备', NULL, 'fd80ebd493a655608dc893a9f897d845', 'YzcmCZNvbXocrsz9dm8e', '[email protected]', '13889700023', 1, 7, 'admin', '2018-09-23 19:43:00', 'admin', '2019-01-10 11:41:13', 0);
INSERT INTO `sys_user`(`id`, `name`, `nick_name`, `avatar`, `password`, `salt`, `email`, `mobile`, `status`, `dept_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (23, 'zhaoyun', '赵云', NULL, 'fd80ebd493a655608dc893a9f897d845', 'YzcmCZNvbXocrsz9dm8e', '[email protected]', '13889700023', 1, 7, 'admin', '2018-09-23 19:43:44', 'admin', '2018-09-23 19:43:52', 0);
INSERT INTO `sys_user`(`id`, `name`, `nick_name`, `avatar`, `password`, `salt`, `email`, `mobile`, `status`, `dept_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (24, 'zhugeliang', '诸葛亮', NULL, 'fd80ebd493a655608dc893a9f897d845', 'YzcmCZNvbXocrsz9dm8e', '[email protected]', '13889700023', 7, 11, 'admin', '2018-09-23 19:44:23', 'admin', '2018-09-23 19:44:29', 0);
INSERT INTO `sys_user`(`id`, `name`, `nick_name`, `avatar`, `password`, `salt`, `email`, `mobile`, `status`, `dept_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (25, 'caocao', '曹操', NULL, 'fd80ebd493a655608dc893a9f897d845', 'YzcmCZNvbXocrsz9dm8e', '[email protected]', '13889700023', 1, 8, 'admin', '2018-09-23 19:45:32', 'admin', '2019-01-10 17:59:14', 0);
INSERT INTO `sys_user`(`id`, `name`, `nick_name`, `avatar`, `password`, `salt`, `email`, `mobile`, `status`, `dept_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (26, 'dianwei', '典韦', NULL, 'fd80ebd493a655608dc893a9f897d845', 'YzcmCZNvbXocrsz9dm8e', '[email protected]', '13889700023', 1, 10, 'admin', '2018-09-23 19:45:48', 'admin', '2018-09-23 19:45:57', 0);
INSERT INTO `sys_user`(`id`, `name`, `nick_name`, `avatar`, `password`, `salt`, `email`, `mobile`, `status`, `dept_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (27, 'xiahoudun', '夏侯惇', NULL, 'fd80ebd493a655608dc893a9f897d845', 'YzcmCZNvbXocrsz9dm8e', '[email protected]', '13889700023', 1, 8, 'admin', '2018-09-23 19:46:09', 'admin', '2018-09-23 19:46:17', 0);
INSERT INTO `sys_user`(`id`, `name`, `nick_name`, `avatar`, `password`, `salt`, `email`, `mobile`, `status`, `dept_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (28, 'xunyu', '荀彧', NULL, 'fd80ebd493a655608dc893a9f897d845', 'YzcmCZNvbXocrsz9dm8e', '[email protected]', '13889700023', 1, 10, 'admin', '2018-09-23 19:46:38', 'admin', '2018-11-04 15:33:17', 0);
INSERT INTO `sys_user`(`id`, `name`, `nick_name`, `avatar`, `password`, `salt`, `email`, `mobile`, `status`, `dept_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (29, 'sunquan', '孙权', NULL, 'fd80ebd493a655608dc893a9f897d845', 'YzcmCZNvbXocrsz9dm8e', '[email protected]', '13889700023', 1, 10, 'admin', '2018-09-23 19:46:54', 'admin', '2018-09-23 19:47:03', 0);
INSERT INTO `sys_user`(`id`, `name`, `nick_name`, `avatar`, `password`, `salt`, `email`, `mobile`, `status`, `dept_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (30, 'zhouyu', '周瑜', NULL, 'fd80ebd493a655608dc893a9f897d845', 'YzcmCZNvbXocrsz9dm8e', '[email protected]', '13889700023', 1, 11, 'admin', '2018-09-23 19:47:28', 'admin', '2018-09-23 19:48:04', 0);
INSERT INTO `sys_user`(`id`, `name`, `nick_name`, `avatar`, `password`, `salt`, `email`, `mobile`, `status`, `dept_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (31, 'luxun', '陆逊', NULL, 'fd80ebd493a655608dc893a9f897d845', 'YzcmCZNvbXocrsz9dm8e', '[email protected]', '13889700023', 1, 11, 'admin', '2018-09-23 19:47:44', 'admin', '2018-09-23 19:47:58', 0);
INSERT INTO `sys_user`(`id`, `name`, `nick_name`, `avatar`, `password`, `salt`, `email`, `mobile`, `status`, `dept_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (32, 'huanggai', '黄盖', NULL, 'fd80ebd493a655608dc893a9f897d845', 'YzcmCZNvbXocrsz9dm8e', '[email protected]', '13889700023', 1, 11, 'admin', '2018-09-23 19:48:38', 'admin', '2018-09-23 19:49:02', 0);
INSERT INTO `sys_user`(`id`, `name`, `nick_name`, `avatar`, `password`, `salt`, `email`, `mobile`, `status`, `dept_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (33, 'zhangsan', '张三', NULL, NULL, NULL, '[email protected]', NULL, NULL, NULL, NULL, NULL, NULL, NULL, 0);
INSERT INTO `sys_user`(`id`, `name`, `nick_name`, `avatar`, `password`, `salt`, `email`, `mobile`, `status`, `dept_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (34, 'zhangsan1', '张三1', NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, 0);
INSERT INTO `sys_user`(`id`, `name`, `nick_name`, `avatar`, `password`, `salt`, `email`, `mobile`, `status`, `dept_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (35, 'zhangsan2', '张三2', NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, 0);
INSERT INTO `sys_user`(`id`, `name`, `nick_name`, `avatar`, `password`, `salt`, `email`, `mobile`, `status`, `dept_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (37, 'zhangsan3', '张三3', NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, 0);
INSERT INTO `sys_user`(`id`, `name`, `nick_name`, `avatar`, `password`, `salt`, `email`, `mobile`, `status`, `dept_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (38, 'zhangsan4', '张三4', NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, 0);
INSERT INTO `sys_user`(`id`, `name`, `nick_name`, `avatar`, `password`, `salt`, `email`, `mobile`, `status`, `dept_id`, `create_by`, `create_time`, `last_update_by`, `last_update_time`, `del_flag`) VALUES (39, 'zhangsan5', '张三5', NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, 0);



这里有四个表,说明一下:sys_usersys_dept是多对一关系,sys_rolesys_user是多对一关系。sys_user_rolesys_usersys_role的关联表,这里主要是之前想在java代码里面操作的时候建立的第三方表,如果直接使用MySQL级联查询,感觉这个是多余的(而且是副作用,读者可以自行体会,但是我们接下来把这个问题都解决了,其他都SO EASY!)。

B、工程代码

新建项目什么的我就不演示了,需要的可以自行查阅相关资料。这里直接给出源码。

pom.xml


<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0modelVersion>
    <parent>
        <groupId>org.springframework.bootgroupId>
        <artifactId>spring-boot-starter-parentartifactId>
        <version>2.2.6.RELEASEversion>
        <relativePath/> 
    parent>
    <groupId>cn.edu.njustgroupId>
    <artifactId>mangoartifactId>
    <version>0.0.1-SNAPSHOTversion>
    <name>mangoname>
    <description>Demo project for Spring Bootdescription>

    <properties>
        <java.version>1.8java.version>
        
        <skipTests>trueskipTests>
    properties>

    <dependencies>


        <dependency>
            <groupId>org.projectlombokgroupId>
            <artifactId>lombokartifactId>
            <optional>trueoptional>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-testartifactId>
            <scope>testscope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintagegroupId>
                    <artifactId>junit-vintage-engineartifactId>
                exclusion>
                <exclusion>
                    <groupId>org.springframework.bootgroupId>
                    <artifactId>spring-boot-starter-loggingartifactId>
                exclusion>
            exclusions>
        dependency>

        <dependency>
            <groupId>io.springfoxgroupId>
            <artifactId>springfox-swagger2artifactId>
            <version>2.9.2version>
        dependency>
        <dependency>
            <groupId>io.springfoxgroupId>
            <artifactId>springfox-swagger-uiartifactId>
            <version>2.9.2version>
        dependency>

        <dependency>
            <groupId>org.mybatis.spring.bootgroupId>
            <artifactId>mybatis-spring-boot-starterartifactId>
            <version>1.3.2version>
        dependency>
        <dependency>
            <groupId>mysqlgroupId>
            <artifactId>mysql-connector-javaartifactId>
            <version>5.1.47version>
        dependency>

        
        <dependency>
            <groupId>tk.mybatisgroupId>
            <artifactId>mapper-spring-boot-starterartifactId>
            <version>1.2.4version>
            <exclusions>
                <exclusion>
                    <artifactId>mybatisartifactId>
                    <groupId>org.mybatisgroupId>
                exclusion>
                <exclusion>
                    <artifactId>mybatis-springartifactId>
                    <groupId>org.mybatisgroupId>
                exclusion>
            exclusions>
        dependency>

        
        <dependency>
            <groupId>com.github.pagehelpergroupId>
            <artifactId>pagehelper-spring-boot-starterartifactId>
            <version>1.2.3version>
            <exclusions>
                <exclusion>
                    <artifactId>mybatis-spring-boot-starterartifactId>
                    <groupId>org.mybatis.spring.bootgroupId>
                exclusion>
            exclusions>
        dependency>

        
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-log4jartifactId>
            <version>1.3.3.RELEASEversion>
        dependency>
        <dependency>
            <groupId>junitgroupId>
            <artifactId>junitartifactId>
            <version>4.12version>
            <scope>testscope>
        dependency>

        
        <dependency>
            <groupId>com.alibabagroupId>
            <artifactId>druid-spring-boot-starterartifactId>
            <version>1.1.10version>
        dependency>
    dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-maven-pluginartifactId>
            plugin>

            
            <plugin>
                <groupId>org.mybatis.generatorgroupId>
                <artifactId>mybatis-generator-maven-pluginartifactId>
                <version>1.3.2version>
                <configuration>
                    <verbose>trueverbose>
                    <overwrite>trueoverwrite>
                configuration>
                <dependencies>
                    <dependency>
                        <groupId>mysqlgroupId>
                        <artifactId>mysql-connector-javaartifactId>
                        <version>5.1.47version>
                    dependency>
                    <dependency>
                        <groupId>tk.mybatisgroupId>
                        <artifactId>mapperartifactId>
                        <version>4.0.0version>
                    dependency>
                dependencies>
            plugin>
        plugins>
    build>


project>

application.yml

server:
  port: 8005

logging:
  config: classpath:log4j.properties
  level:
    dao: debug
    org:
      mybatis: debug

spring:
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    username: root
    password: root
    url: jdbc:mysql://localhost:3306/mango?serverTimezone=UTC&useUnicode=true&characterEncoding=UTF-8
    druid:
      driver-class-name: com.mysql.jdbc.Driver
      url: jdbc:mysql://localhost:3306/mango?useUnicode=true&zeroDateTimeBehavior=convertToNull&autoReconnect=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC
      username: root
      password: root
      filters: stat,wall,log4j,config
      max-active: 100
      initial-size: 1
      max-wait: 60000
      min-idle: 1
      time-between-eviction-runs-millis: 60000
      min-evictable-idle-time-millis: 300000
      validation-query: select 'x'
      test-while-idle: true
      test-on-borrow: false
      test-on-return: false
      pool-prepared-statements: true
      max-open-prepared-statements: 50
      max-pool-prepared-statement-per-connection-size: 20

  jackson:
    default-property-inclusion: non_null

# 指定数据库中表生成实体的路径
mybatis:
  type-aliases-package: cn.edu.njust.mango.entity
  mapper-locations: classpath:mapper/*.xml
  configuration:
    #    输出sql日志信息
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl


#pagehelper
pagehelper:
  helperDialect: mysql
  reasonable: true
  supportMethodsArguments: true
  params:
    count: countSql

log4j.properties

#Console Log
log4j.rootLogger=INFO,console,debug,info,warn,error

LOG_PATTERN=[%d{yyyy-MM-dd HH:mm:ss.SSS}] boot%X{context} - %5p [%t] --- %c{1}: %m%n

#A1--Print log to Console
log4j.appender.console=org.apache.log4j.ConsoleAppender
log4j.appender.console.Threshold=DEBUG
log4j.appender.console.layout=org.apache.log4j.PatternLayout
log4j.appender.console.layout.ConversionPattern=${LOG_PATTERN}

log4j.appender.info=org.apache.log4j.DailyRollingFileAppender
log4j.appender.info.Threshold=INFO
log4j.appender.info.File=${LOG_PATH}/${LOG_FILE}_info.log
log4j.appender.info.DatePattern='.'yyyy-MM-dd
log4j.appender.info.layout = org.apache.log4j.PatternLayout
log4j.appender.info.layout.ConversionPattern=${LOG_PATTERN}

log4j.appender.error=org.apache.log4j.DailyRollingFileAppender
log4j.appender.error.Threshold=ERROR
log4j.appender.error.File=${LOG_PATH}/${LOG_FILE}_error.log
log4j.appender.error.DatePattern='.'yyyy-MM-dd
log4j.appender.error.layout = org.apache.log4j.PatternLayout
log4j.appender.error.layout.ConversionPattern=${LOG_PATTERN}


log4j.appender.debug=org.apache.log4j.DailyRollingFileAppender
log4j.appender.debug.Threshold=DEBUG
log4j.appender.debug.File=${LOG_PATH}/${LOG_FILE}_debug.log
log4j.appender.debug.DatePattern='.'yyyy-MM-dd
log4j.appender.debug.layout = org.apache.log4j.PatternLayout
log4j.appender.debug.layout.ConversionPattern=${LOG_PATTERN}

log4j.appender.warn=org.apache.log4j.DailyRollingFileAppender
log4j.appender.warn.Threshold=WARN
log4j.appender.warn.File=${LOG_PATH}/${LOG_FILE}_warn.log
log4j.appender.warn.DatePattern='.'yyyy-MM-dd
log4j.appender.warn.layout = org.apache.log4j.PatternLayout
log4j.appender.warn.layout.ConversionPattern=${LOG_PATTERN}

SysUser.java

package cn.edu.njust.mango.entity;

import io.swagger.annotations.ApiModel;
import lombok.Data;

import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import java.io.Serializable;
import java.util.Date;

/**
 * 用户管理(SysUser)实体类
 *
 * @author Chen
 * @since 2020-05-06 15:24:25
 */
@Data
@ApiModel("用户管理")
public class SysUser implements Serializable {
    private static final long serialVersionUID = -44575028142368237L;

    /**
    * 编号
    */
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    /**
    * 用户名
    */
    private String name;

    /**
    * 昵称
    */
    private String nickName;

    /**
    * 头像
    */
    private String avatar;

    /**
    * 密码
    */
    private String password;

    /**
    * 加密盐
    */
    private String salt;

    /**
    * 邮箱
    */
    private String email;

    /**
    * 手机号
    */
    private String mobile;

    /**
    * 状态  0:禁用   1:正常
    */
    private Object status;

    /**
    * 机构ID
    */
    private Long deptId;

    /**
    * 创建人
    */
    private String createBy;

    /**
    * 创建时间
    */
    private Date createTime;

    /**
    * 更新人
    */
    private String lastUpdateBy;

    /**
    * 更新时间
    */
    private Date lastUpdateTime;

    /**
    * 是否删除  -1:已删除  0:正常
    */
    private Object delFlag;

}

SysUserRole.java

package cn.edu.njust.mango.entity;

import java.util.Date;
import javax.persistence.GeneratedValue;
import java.io.Serializable;
import io.swagger.annotations.*;
import lombok.Data;
import javax.persistence.*;

/**
 * 用户角色(SysUserRole)实体类
 *
 * @author Chen
 * @since 2020-05-06 15:24:25
 */
@Data
@ApiModel("用户角色")
public class SysUserRole implements Serializable {
    private static final long serialVersionUID = -48730270108013484L;

    /**
    * 编号
    */
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    /**
    * 用户ID
    */
    private Long userId;

    /**
    * 角色ID
    */
    private Long roleId;

    /**
    * 创建人
    */
    private String createBy;

    /**
    * 创建时间
    */
    private Date createTime;

    /**
    * 更新人
    */
    private String lastUpdateBy;

    /**
    * 更新时间
    */
    private Date lastUpdateTime;


}

SysRole.java

package cn.edu.njust.mango.entity;

import java.util.Date;
import javax.persistence.GeneratedValue;
import java.io.Serializable;
import io.swagger.annotations.*;
import lombok.Data;
import javax.persistence.*;

/**
 * 角色管理(SysRole)实体类
 *
 * @author Chen
 * @since 2020-05-06 15:24:25
 */
@Data
@ApiModel("角色管理")
public class SysRole implements Serializable {
    private static final long serialVersionUID = -79886721138103042L;

    /**
    * 编号
    */
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    /**
    * 角色名称
    */
    private String name;

    /**
    * 备注
    */
    private String remark;

    /**
    * 创建人
    */
    private String createBy;

    /**
    * 创建时间
    */
    private Date createTime;

    /**
    * 更新人
    */
    private String lastUpdateBy;

    /**
    * 更新时间
    */
    private Date lastUpdateTime;

    /**
    * 是否删除  -1:已删除  0:正常
    */
    private Object delFlag;


}

SysDept.java

package cn.edu.njust.mango.entity;

import io.swagger.annotations.ApiModel;
import lombok.Data;

import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import java.io.Serializable;
import java.util.Date;

/**
 * 机构管理(SysDept)实体类
 *
 * @author Chen
 * @since 2020-05-06 15:24:25
 */
@Data
@ApiModel("机构管理")
public class SysDept implements Serializable {
    private static final long serialVersionUID = -50559626000073116L;

    /**
    * 编号
    */
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    /**
    * 机构名称
    */
    private String name;

    /**
    * 上级机构ID,一级机构为0
    */
    private Long parentId;

    /**
    * 排序
    */
    private Integer orderNum;

    /**
    * 创建人
    */
    private String createBy;

    /**
    * 创建时间
    */
    private Date createTime;

    /**
    * 更新人
    */
    private String lastUpdateBy;

    /**
    * 更新时间
    */
    private Date lastUpdateTime;

    /**
    * 是否删除  -1:已删除  0:正常
    */
    private Object delFlag;


}

SysUserVO.java 这里为了不和单表操作相耦合,直接搞一个VO类,里面存放多对一及一对多的数据。

package cn.edu.njust.mango.vo;

import cn.edu.njust.mango.entity.SysDept;
import cn.edu.njust.mango.entity.SysRole;
import cn.edu.njust.mango.entity.SysUser;
import lombok.Data;

import java.util.List;

/**
 * @author Chen
 * @version 1.0
 * @date 2020/5/7 7:31
 * @description:
 */
@Data
public class SysUserVO extends SysUser {
    /**
     * 非数据库字段
     */
    private SysDept dept;

    /**
     * 非数据库字段
     */
    private List<SysRole> roles;
}

SysUserMapper.xml



<mapper namespace="cn.edu.njust.mango.mapper.SysUserMapper">

    <resultMap type="cn.edu.njust.mango.entity.SysUser" id="SysUserMap">
        <result property="id" column="id" jdbcType="INTEGER"/>
        <result property="name" column="name" jdbcType="VARCHAR"/>
        <result property="nickName" column="nick_name" jdbcType="VARCHAR"/>
        <result property="avatar" column="avatar" jdbcType="VARCHAR"/>
        <result property="password" column="password" jdbcType="VARCHAR"/>
        <result property="salt" column="salt" jdbcType="VARCHAR"/>
        <result property="email" column="email" jdbcType="VARCHAR"/>
        <result property="mobile" column="mobile" jdbcType="VARCHAR"/>
        <result property="status" column="status" jdbcType="OTHER"/>
        <result property="deptId" column="dept_id" jdbcType="INTEGER"/>
        <result property="createBy" column="create_by" jdbcType="VARCHAR"/>
        <result property="createTime" column="create_time" jdbcType="TIMESTAMP"/>
        <result property="lastUpdateBy" column="last_update_by" jdbcType="VARCHAR"/>
        <result property="lastUpdateTime" column="last_update_time" jdbcType="TIMESTAMP"/>
        <result property="delFlag" column="del_flag" jdbcType="OTHER"/>
    resultMap>


    <resultMap id="queryForListMap" type="cn.edu.njust.mango.vo.SysUserVO">
        <id column="id" property="id" jdbcType="INTEGER"/>
        <result property="name" column="name" jdbcType="VARCHAR"/>
        <result property="nickName" column="nick_name" jdbcType="VARCHAR"/>
        <result property="avatar" column="avatar" jdbcType="VARCHAR"/>
        <result property="password" column="password" jdbcType="VARCHAR"/>
        <result property="salt" column="salt" jdbcType="VARCHAR"/>
        <result property="email" column="email" jdbcType="VARCHAR"/>
        <result property="mobile" column="mobile" jdbcType="VARCHAR"/>
        <result property="status" column="status" jdbcType="OTHER"/>
        <result property="deptId" column="dept_id" jdbcType="INTEGER"/>
        <result property="createBy" column="create_by" jdbcType="VARCHAR"/>
        <result property="createTime" column="create_time" jdbcType="TIMESTAMP"/>
        <result property="lastUpdateBy" column="last_update_by" jdbcType="VARCHAR"/>
        <result property="lastUpdateTime" column="last_update_time" jdbcType="TIMESTAMP"/>
        <result property="delFlag" column="del_flag" jdbcType="OTHER"/>
        <association property="dept" javaType="cn.edu.njust.mango.entity.SysDept">
            <id property="id" column="d_id" jdbcType="INTEGER"/>
            <result property="name" column="d_name" jdbcType="VARCHAR"/>
            <result property="parentId" column="d_parent_id" jdbcType="INTEGER"/>
            <result property="orderNum" column="d_order_num" jdbcType="INTEGER"/>
            <result property="createBy" column="d_create_by" jdbcType="VARCHAR"/>
            <result property="createTime" column="d_create_time" jdbcType="TIMESTAMP"/>
            <result property="lastUpdateBy" column="d_last_update_by" jdbcType="VARCHAR"/>
            <result property="lastUpdateTime" column="d_last_update_time" jdbcType="TIMESTAMP"/>
            <result property="delFlag" column="d_del_flag" jdbcType="OTHER"/>
        association>
        <collection property="roles" javaType="java.util.List" ofType="cn.edu.njust.mango.entity.SysRole">
            <id column="role_id" property="id" jdbcType="INTEGER"/>
            <result property="name" column="role_name" jdbcType="VARCHAR"/>
            <result property="remark" column="role_remark" jdbcType="VARCHAR"/>
            <result property="createBy" column="role_create_by" jdbcType="VARCHAR"/>
            <result property="createTime" column="role_create_time" jdbcType="TIMESTAMP"/>
            <result property="lastUpdateBy" column="role_last_update_by" jdbcType="VARCHAR"/>
            <result property="lastUpdateTime" column="role_last_update_time" jdbcType="TIMESTAMP"/>
            <result property="delFlag" column="role_del_flag" jdbcType="OTHER"/>
        collection>
    resultMap>

    <select id="getDept" resultType="cn.edu.njust.mango.entity.SysDept" parameterType="INTEGER">
		SELECT
			*
		FROM sys_dept d
		where id = #{dept_id}
	select>

    <select id="queryAllByPageRequestAndConditionAndRoleAndDept" resultType="cn.edu.njust.mango.vo.SysUserVO">
        SELECT
            *
        FROM
            sys_user u
            LEFT JOIN sys_user_role ru ON u.id = ru.user_id
            LEFT JOIN sys_role r on r.id = ru.role_id
            LEFT JOIN sys_dept d on d.id = u.dept_id
    select>

mapper>

SysUserMapper.java

package cn.edu.njust.mango.mapper;

import cn.edu.njust.mango.base.mapper.IBaseMapper;
import cn.edu.njust.mango.entity.SysUser;
import cn.edu.njust.mango.pojo.PageRequest;
import cn.edu.njust.mango.vo.SysUserVO;

import java.util.List;


/**
 * 用户管理(SysUser)表数据库访问层
 *
 * @author Chen
 * @since 2020-05-06 14:16:48
 */
public interface SysUserMapper extends IBaseMapper<SysUser> {
    List<SysUserVO> queryAllByPageRequestAndConditionAndRoleAndDept(PageRequest pageRequest);
}

SysUserMapperTest1.java

package cn.edu.njust.mango.mapper;

import cn.edu.njust.mango.pojo.PageRequest;
import cn.edu.njust.mango.vo.SysUserVO;
import org.junit.jupiter.api.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.util.List;

/**
 * @author Chen
 * @version 1.0
 * @date 2020/5/7 15:34
 * @description:
 */
@SpringBootTest
@RunWith(JUnit4.class)
class SysUserMapperTest1 {

    @Autowired
    private SysUserMapper sysUserMapper;

    @Test
    void queryAllByPageRequestAndConditionAndRoleAndDept() {
        PageRequest pageRequest = new PageRequest();
        pageRequest.setPageSize(100);
        List<SysUserVO> sysUserVOS = sysUserMapper.queryAllByPageRequestAndConditionAndRoleAndDept(pageRequest);
        System.out.println(sysUserVOS);
    }

}

3、问题解决

好了工程搭建完毕,我们开始跑程序了。为了方便测试,我们打断点查看数据。直接运行测试类。控制台输出如下:

在这里插入图片描述

我们在System.out.println(sysUserVOS);处打断点。

Mybatis级联查询(多对一、一对多)Demo及问题_第1张图片
然后我们查看数据全是null,难道是我们的多对一,一对多没有设置成功?但是我们查看SQL语句日志,确实是执行了啊!

java

JDBC Connection [com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl@672d8370] will not be managed by Spring
==>  Preparing: SELECT count(0) FROM sys_user u LEFT JOIN sys_user_role ru ON u.id = ru.user_id LEFT JOIN sys_role r ON r.id = ru.role_id LEFT JOIN sys_dept d ON d.id = u.dept_id 
==> Parameters: 
<==    Columns: count(0)
<==        Row: 20
<==      Total: 1
==>  Preparing: SELECT * FROM sys_user u LEFT JOIN sys_user_role ru ON u.id = ru.user_id LEFT JOIN sys_role r on r.id = ru.role_id LEFT JOIN sys_dept d on d.id = u.dept_id LIMIT ? 
==> Parameters: 100(Integer)
<==    Columns: id, name, nick_name, avatar, password, salt, email, mobile, status, dept_id, create_by, create_time, last_update_by, last_update_time, del_flag, id, user_id, role_id, create_by, create_time, last_update_by, last_update_time, id, name, remark, create_by, create_time, last_update_by, last_update_time, del_flag, id, name, parent_id, order_num, create_by, create_time, last_update_by, last_update_time, del_flag
<==        Row: 1, admin, 字节跳动万岁, null, bd1718f058d8a02468134432b8656a86, YzcmCZNvbXocrsz9dm8e, admin@qq.com, 13612345678, 1, 4, admin, 2018-08-14 11:11:11.0, admin, 2018-08-14 11:11:11.0, 0, 1, 1, 1, null, null, null, null, 1, admin, 超级管理员, admin, 2019-01-19 11:11:11.0, admin, 2019-01-19 19:07:18.0, 0, 4, 上海分公司, 2, 0, admin, 2018-09-23 19:37:03.0, null, null, 0
<==        Row: 31, luxun, 陆逊, null, fd80ebd493a655608dc893a9f897d845, YzcmCZNvbXocrsz9dm8e, test@qq.com, 13889700023, 1, 11, admin, 2018-09-23 19:47:44.0, admin, 2018-09-23 19:47:58.0, 0, 57, 31, 2, null, null, null, null, 2, mng, 项目经理, admin, 2019-01-19 11:11:11.0, admin, 2019-01-19 11:39:28.0, 0, 11, 市场部, 6, 0, admin, 2018-09-23 19:39:01.0, null, null, 0
<==        Row: 30, zhouyu, 周瑜, null, fd80ebd493a655608dc893a9f897d845, YzcmCZNvbXocrsz9dm8e, test@qq.com, 13889700023, 1, 11, admin, 2018-09-23 19:47:28.0, admin, 2018-09-23 19:48:04.0, 0, 58, 30, 2, null, null, null, null, 2, mng, 项目经理, admin, 2019-01-19 11:11:11.0, admin, 2019-01-19 11:39:28.0, 0, 11, 市场部, 6, 0, admin, 2018-09-23 19:39:01.0, null, null, 0
<==        Row: 32, huanggai, 黄盖, null, fd80ebd493a655608dc893a9f897d845, YzcmCZNvbXocrsz9dm8e, test@qq.com, 13889700023, 1, 11, admin, 2018-09-23 19:48:38.0, admin, 2018-09-23 19:49:02.0, 0, 59, 32, 3, null, null, null, null, 3, chenwei, 陈伟, admin, 2020-05-07 15:52:53.0, admin, 2020-05-07 15:52:59.0, 0, 11, 市场部, 6, 0, admin, 2018-09-23 19:39:01.0, null, null, 0
<==        Row: 33, zhangsan, 张三, null, null, null, 206@qq.com1, null, null, null, null, null, null, null, 0, 73, 33, 8, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null
<==        Row: 25, caocao, 曹操, null, fd80ebd493a655608dc893a9f897d845, YzcmCZNvbXocrsz9dm8e, test@qq.com, 13889700023, 1, 8, admin, 2018-09-23 19:45:32.0, admin, 2019-01-10 17:59:14.0, 0, 74, 25, 8, null, null, null, null, null, null, null, null, null, null, null, null, 8, 技术部, 4, 0, admin, 2018-09-23 19:38:10.0, null, null, 0
<==        Row: 25, caocao, 曹操, null, fd80ebd493a655608dc893a9f897d845, YzcmCZNvbXocrsz9dm8e, test@qq.com, 13889700023, 1, 8, admin, 2018-09-23 19:45:32.0, admin, 2019-01-10 17:59:14.0, 0, 75, 25, 2, null, null, null, null, 2, mng, 项目经理, admin, 2019-01-19 11:11:11.0, admin, 2019-01-19 11:39:28.0, 0, 8, 技术部, 4, 0, admin, 2018-09-23 19:38:10.0, null, null, 0
<==        Row: 22, liubei, 刘备, null, fd80ebd493a655608dc893a9f897d845, YzcmCZNvbXocrsz9dm8e, test@qq.com, 13889700023, 1, 7, admin, 2018-09-23 19:43:00.0, admin, 2019-01-10 11:41:13.0, 0, 80, 22, 2, null, null, null, null, 2, mng, 项目经理, admin, 2019-01-19 11:11:11.0, admin, 2019-01-19 11:39:28.0, 0, 7, 技术部, 5, 0, admin, 2018-09-23 19:38:00.0, null, null, 0
<==        Row: 23, zhaoyun, 赵云, null, fd80ebd493a655608dc893a9f897d845, YzcmCZNvbXocrsz9dm8e, test@qq.com, 13889700023, 1, 7, admin, 2018-09-23 19:43:44.0, admin, 2018-09-23 19:43:52.0, 0, 81, 23, 3, null, null, null, null, 3, chenwei, 陈伟, admin, 2020-05-07 15:52:53.0, admin, 2020-05-07 15:52:59.0, 0, 7, 技术部, 5, 0, admin, 2018-09-23 19:38:00.0, null, null, 0
<==        Row: 24, zhugeliang, 诸葛亮, null, fd80ebd493a655608dc893a9f897d845, YzcmCZNvbXocrsz9dm8e, test@qq.com, 13889700023, 7, 11, admin, 2018-09-23 19:44:23.0, admin, 2018-09-23 19:44:29.0, 0, 82, 24, 4, null, null, null, null, 4, test, 测试人员, admin, 2019-01-19 11:11:11.0, admin, 2019-01-19 11:11:11.0, 0, 11, 市场部, 6, 0, admin, 2018-09-23 19:39:01.0, null, null, 0
<==        Row: 26, dianwei, 典韦, null, fd80ebd493a655608dc893a9f897d845, YzcmCZNvbXocrsz9dm8e, test@qq.com, 13889700023, 1, 10, admin, 2018-09-23 19:45:48.0, admin, 2018-09-23 19:45:57.0, 0, 83, 26, 3, null, null, null, null, 3, chenwei, 陈伟, admin, 2020-05-07 15:52:53.0, admin, 2020-05-07 15:52:59.0, 0, 10, 市场部, 5, 0, admin, 2018-09-23 19:38:45.0, null, null, 0
<==        Row: 29, sunquan, 孙权, null, fd80ebd493a655608dc893a9f897d845, YzcmCZNvbXocrsz9dm8e, test@qq.com, 13889700023, 1, 10, admin, 2018-09-23 19:46:54.0, admin, 2018-09-23 19:47:03.0, 0, 85, 29, 2, null, null, null, null, 2, mng, 项目经理, admin, 2019-01-19 11:11:11.0, admin, 2019-01-19 11:39:28.0, 0, 10, 市场部, 5, 0, admin, 2018-09-23 19:38:45.0, null, null, 0
<==        Row: 28, xunyu, 荀彧, null, fd80ebd493a655608dc893a9f897d845, YzcmCZNvbXocrsz9dm8e, test@qq.com, 13889700023, 1, 10, admin, 2018-09-23 19:46:38.0, admin, 2018-11-04 15:33:17.0, 0, 86, 28, 4, null, null, null, null, 4, test, 测试人员, admin, 2019-01-19 11:11:11.0, admin, 2019-01-19 11:11:11.0, 0, 10, 市场部, 5, 0, admin, 2018-09-23 19:38:45.0, null, null, 0
<==        Row: 27, xiahoudun, 夏侯惇, null, fd80ebd493a655608dc893a9f897d845, YzcmCZNvbXocrsz9dm8e, test@qq.com, 13889700023, 1, 8, admin, 2018-09-23 19:46:09.0, admin, 2018-09-23 19:46:17.0, 0, 87, 27, 3, null, null, null, null, 3, chenwei, 陈伟, admin, 2020-05-07 15:52:53.0, admin, 2020-05-07 15:52:59.0, 0, 8, 技术部, 4, 0, admin, 2018-09-23 19:38:10.0, null, null, 0
<==        Row: 39, zhangsan5, 张三5, null, null, null, null, null, null, null, null, null, null, null, 0, 88, 39, 4, null, null, null, null, 4, test, 测试人员, admin, 2019-01-19 11:11:11.0, admin, 2019-01-19 11:11:11.0, 0, null, null, null, null, null, null, null, null, null
<==        Row: 39, zhangsan5, 张三5, null, null, null, null, null, null, null, null, null, null, null, 0, 89, 39, 3, null, null, null, null, 3, chenwei, 陈伟, admin, 2020-05-07 15:52:53.0, admin, 2020-05-07 15:52:59.0, 0, null, null, null, null, null, null, null, null, null
<==        Row: 34, zhangsan1, 张三1, null, null, null, null, null, null, null, null, null, null, null, 0, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null
<==        Row: 35, zhangsan2, 张三2, null, null, null, null, null, null, null, null, null, null, null, 0, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null
<==        Row: 37, zhangsan3, 张三3, null, null, null, null, null, null, null, null, null, null, null, 0, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null
<==        Row: 38, zhangsan4, 张三4, null, null, null, null, null, null, null, null, null, null, null, 0, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null
<==      Total: 20

嗯回头看代码是这里出了问题。

Mybatis级联查询(多对一、一对多)Demo及问题_第2张图片

当我们设置了Map之后,这里应该使用我们的Map了,而不是使用实体对象,修改该文件。

SysUserMapper.xml



<mapper namespace="cn.edu.njust.mango.mapper.SysUserMapper">

    <resultMap type="cn.edu.njust.mango.entity.SysUser" id="SysUserMap">
        <result property="id" column="id" jdbcType="INTEGER"/>
        <result property="name" column="name" jdbcType="VARCHAR"/>
        <result property="nickName" column="nick_name" jdbcType="VARCHAR"/>
        <result property="avatar" column="avatar" jdbcType="VARCHAR"/>
        <result property="password" column="password" jdbcType="VARCHAR"/>
        <result property="salt" column="salt" jdbcType="VARCHAR"/>
        <result property="email" column="email" jdbcType="VARCHAR"/>
        <result property="mobile" column="mobile" jdbcType="VARCHAR"/>
        <result property="status" column="status" jdbcType="OTHER"/>
        <result property="deptId" column="dept_id" jdbcType="INTEGER"/>
        <result property="createBy" column="create_by" jdbcType="VARCHAR"/>
        <result property="createTime" column="create_time" jdbcType="TIMESTAMP"/>
        <result property="lastUpdateBy" column="last_update_by" jdbcType="VARCHAR"/>
        <result property="lastUpdateTime" column="last_update_time" jdbcType="TIMESTAMP"/>
        <result property="delFlag" column="del_flag" jdbcType="OTHER"/>
    resultMap>


    <resultMap id="queryForListMap" type="cn.edu.njust.mango.vo.SysUserVO">
        <id column="id" property="id" jdbcType="INTEGER"/>
        <result property="name" column="name" jdbcType="VARCHAR"/>
        <result property="nickName" column="nick_name" jdbcType="VARCHAR"/>
        <result property="avatar" column="avatar" jdbcType="VARCHAR"/>
        <result property="password" column="password" jdbcType="VARCHAR"/>
        <result property="salt" column="salt" jdbcType="VARCHAR"/>
        <result property="email" column="email" jdbcType="VARCHAR"/>
        <result property="mobile" column="mobile" jdbcType="VARCHAR"/>
        <result property="status" column="status" jdbcType="OTHER"/>
        <result property="deptId" column="dept_id" jdbcType="INTEGER"/>
        <result property="createBy" column="create_by" jdbcType="VARCHAR"/>
        <result property="createTime" column="create_time" jdbcType="TIMESTAMP"/>
        <result property="lastUpdateBy" column="last_update_by" jdbcType="VARCHAR"/>
        <result property="lastUpdateTime" column="last_update_time" jdbcType="TIMESTAMP"/>
        <result property="delFlag" column="del_flag" jdbcType="OTHER"/>
        <association property="dept" javaType="cn.edu.njust.mango.entity.SysDept">
            <id property="id" column="d_id" jdbcType="INTEGER"/>
            <result property="name" column="d_name" jdbcType="VARCHAR"/>
            <result property="parentId" column="d_parent_id" jdbcType="INTEGER"/>
            <result property="orderNum" column="d_order_num" jdbcType="INTEGER"/>
            <result property="createBy" column="d_create_by" jdbcType="VARCHAR"/>
            <result property="createTime" column="d_create_time" jdbcType="TIMESTAMP"/>
            <result property="lastUpdateBy" column="d_last_update_by" jdbcType="VARCHAR"/>
            <result property="lastUpdateTime" column="d_last_update_time" jdbcType="TIMESTAMP"/>
            <result property="delFlag" column="d_del_flag" jdbcType="OTHER"/>
        association>
        <collection property="roles" javaType="java.util.List" ofType="cn.edu.njust.mango.entity.SysRole">
            <id column="role_id" property="id" jdbcType="INTEGER"/>
            <result property="name" column="role_name" jdbcType="VARCHAR"/>
            <result property="remark" column="role_remark" jdbcType="VARCHAR"/>
            <result property="createBy" column="role_create_by" jdbcType="VARCHAR"/>
            <result property="createTime" column="role_create_time" jdbcType="TIMESTAMP"/>
            <result property="lastUpdateBy" column="role_last_update_by" jdbcType="VARCHAR"/>
            <result property="lastUpdateTime" column="role_last_update_time" jdbcType="TIMESTAMP"/>
            <result property="delFlag" column="role_del_flag" jdbcType="OTHER"/>
        collection>
    resultMap>

    <select id="getDept" resultType="cn.edu.njust.mango.entity.SysDept" parameterType="INTEGER">
		SELECT
			*
		FROM sys_dept d
		where id = #{dept_id}
	select>

    <select id="queryAllByPageRequestAndConditionAndRoleAndDept" resultMap="queryForListMap">
        SELECT
            *
        FROM
            sys_user u
            LEFT JOIN sys_user_role ru ON u.id = ru.user_id
            LEFT JOIN sys_role r on r.id = ru.role_id
            LEFT JOIN sys_dept d on d.id = u.dept_id
    select>

mapper>

我之所以不厌其烦的贴出所有代码,是怕部分读者在实际操作的时候出现错误。这里就暂且麻烦一点,其实只是改成这样。

Mybatis级联查询(多对一、一对多)Demo及问题_第3张图片
接下来再Debug

Mybatis级联查询(多对一、一对多)Demo及问题_第4张图片
一阵窃喜,好像成功了,有数据了。但是真的是这样吗?我们展开其中的一个数据。

Mybatis级联查询(多对一、一对多)Demo及问题_第5张图片
咱就拿zhangsan5举例吧!这里好多数据是空的,但是数据库不是这样的啊!

39	zhangsan5	张三5												0	88	39	4					4	test	测试人员	admin	2019-01-19 11:11:11	admin	2019-01-19 11:11:11	0
39	zhangsan5	张三5												0	89	39	3					3	chenwei	陈伟	admin	2020-05-07 15:52:53	admin	2020-05-07 15:52:59	0

Mybatis级联查询(多对一、一对多)Demo及问题_第6张图片
这里由于数据太多,不好截图,读者可以运行源代码查看,这里我把zhangsan5的两条数据选中了。我们明明发现remark是有值的,但是查询的时候没有出来,而且查询结果的名称也不对。这里主要是不同表的名称有重复。我们需要起别名。还是修改select语句,修改成如下样式。

Mybatis级联查询(多对一、一对多)Demo及问题_第7张图片
完整代码如下:

SysUserMapper.xml



<mapper namespace="cn.edu.njust.mango.mapper.SysUserMapper">

    <resultMap type="cn.edu.njust.mango.entity.SysUser" id="SysUserMap">
        <result property="id" column="id" jdbcType="INTEGER"/>
        <result property="name" column="name" jdbcType="VARCHAR"/>
        <result property="nickName" column="nick_name" jdbcType="VARCHAR"/>
        <result property="avatar" column="avatar" jdbcType="VARCHAR"/>
        <result property="password" column="password" jdbcType="VARCHAR"/>
        <result property="salt" column="salt" jdbcType="VARCHAR"/>
        <result property="email" column="email" jdbcType="VARCHAR"/>
        <result property="mobile" column="mobile" jdbcType="VARCHAR"/>
        <result property="status" column="status" jdbcType="OTHER"/>
        <result property="deptId" column="dept_id" jdbcType="INTEGER"/>
        <result property="createBy" column="create_by" jdbcType="VARCHAR"/>
        <result property="createTime" column="create_time" jdbcType="TIMESTAMP"/>
        <result property="lastUpdateBy" column="last_update_by" jdbcType="VARCHAR"/>
        <result property="lastUpdateTime" column="last_update_time" jdbcType="TIMESTAMP"/>
        <result property="delFlag" column="del_flag" jdbcType="OTHER"/>
    resultMap>


    <resultMap id="queryForListMap" type="cn.edu.njust.mango.vo.SysUserVO">
        <id column="id" property="id" jdbcType="INTEGER"/>
        <result property="name" column="name" jdbcType="VARCHAR"/>
        <result property="nickName" column="nick_name" jdbcType="VARCHAR"/>
        <result property="avatar" column="avatar" jdbcType="VARCHAR"/>
        <result property="password" column="password" jdbcType="VARCHAR"/>
        <result property="salt" column="salt" jdbcType="VARCHAR"/>
        <result property="email" column="email" jdbcType="VARCHAR"/>
        <result property="mobile" column="mobile" jdbcType="VARCHAR"/>
        <result property="status" column="status" jdbcType="OTHER"/>
        <result property="deptId" column="dept_id" jdbcType="INTEGER"/>
        <result property="createBy" column="create_by" jdbcType="VARCHAR"/>
        <result property="createTime" column="create_time" jdbcType="TIMESTAMP"/>
        <result property="lastUpdateBy" column="last_update_by" jdbcType="VARCHAR"/>
        <result property="lastUpdateTime" column="last_update_time" jdbcType="TIMESTAMP"/>
        <result property="delFlag" column="del_flag" jdbcType="OTHER"/>
        <association property="dept" javaType="cn.edu.njust.mango.entity.SysDept">
            <id property="id" column="d_id" jdbcType="INTEGER"/>
            <result property="name" column="d_name" jdbcType="VARCHAR"/>
            <result property="parentId" column="d_parent_id" jdbcType="INTEGER"/>
            <result property="orderNum" column="d_order_num" jdbcType="INTEGER"/>
            <result property="createBy" column="d_create_by" jdbcType="VARCHAR"/>
            <result property="createTime" column="d_create_time" jdbcType="TIMESTAMP"/>
            <result property="lastUpdateBy" column="d_last_update_by" jdbcType="VARCHAR"/>
            <result property="lastUpdateTime" column="d_last_update_time" jdbcType="TIMESTAMP"/>
            <result property="delFlag" column="d_del_flag" jdbcType="OTHER"/>
        association>
        <collection property="roles" javaType="java.util.List" ofType="cn.edu.njust.mango.entity.SysRole">
            <id column="role_id" property="id" jdbcType="INTEGER"/>
            <result property="name" column="role_name" jdbcType="VARCHAR"/>
            <result property="remark" column="role_remark" jdbcType="VARCHAR"/>
            <result property="createBy" column="role_create_by" jdbcType="VARCHAR"/>
            <result property="createTime" column="role_create_time" jdbcType="TIMESTAMP"/>
            <result property="lastUpdateBy" column="role_last_update_by" jdbcType="VARCHAR"/>
            <result property="lastUpdateTime" column="role_last_update_time" jdbcType="TIMESTAMP"/>
            <result property="delFlag" column="role_del_flag" jdbcType="OTHER"/>
        collection>
    resultMap>

    <select id="getDept" resultType="cn.edu.njust.mango.entity.SysDept" parameterType="INTEGER">
		SELECT
			*
		FROM sys_dept d
		where id = #{dept_id}
	select>

    <select id="queryAllByPageRequestAndConditionAndRoleAndDept" resultMap="queryForListMap">
        SELECT
            u.*,
            d.id as d_id,
            d.name as  d_name,
            d.parent_id   as  d_parent_id,
            d.order_num   as  d_order_num,
            d.create_by   as  d_create_by,
            d.create_time   as  d_create_time,
            d.last_update_by   as  d_last_update_by,
            d.last_update_time   as  d_last_update_time,
            d.del_flag   as  d_del_flag,
            r.id as 'role_id',
            r.name as 'role_name',
            r.remark as 'role_remark',
            r.create_by as 'role_create_by',
            r.create_time as 'role_create_time',
            r.last_update_by as 'role_last_update_by',
            r.last_update_time as 'role_last_update_time',
            r.del_flag as 'role_del_flag'
        FROM
            sys_user u
            LEFT JOIN sys_user_role ru ON u.id = ru.user_id
            LEFT JOIN sys_role r on r.id = ru.role_id
            LEFT JOIN sys_dept d on d.id = u.dept_id
    select>

mapper>

再次debug

Mybatis级联查询(多对一、一对多)Demo及问题_第8张图片
我们发现张三5的数据成功上来了,成功解决。

4、总结

  书上的代码直接运行绝大部分是对的,但是总有一些软件的更新使得作者无能为力。之前的API是对的,但是之后就废弃了或修改了是常有的事。所以我们需要跟踪源代码。这只是一个小小的问题,如果没有前辈的无私奉献,很难想象我们自己一天能学到多少内容。感谢各位前辈的辛勤付出,让我们少走了很多的弯路!

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