作业1：多表查询

数据准备：

重新创建一个数据库 db03_homework
执行如下脚本，创建表结构，导入测试数据

-- 部门管理
create table tb_dept(id int unsigned primary key auto_increment comment '主键ID',name varchar(10) not null unique comment '部门名称',create_time datetime not null comment '创建时间',update_time datetime not null comment '修改时间'
) comment '部门表';insert into tb_dept (id, name, create_time, update_time) values(1,'学工部',now(),now()),(2,'教研部',now(),now()),(3,'咨询部',now(),now()), (4,'就业部',now(),now()),(5,'人事部',now(),now());-- 员工管理
create table tb_emp (id int unsigned primary key auto_increment comment 'ID',username varchar(20) not null unique comment '用户名',password varchar(32) default '123456' comment '密码',name varchar(10) not null comment '姓名',gender tinyint unsigned not null comment '性别, 说明: 1 男, 2 女',image varchar(300) comment '图像',job tinyint unsigned comment '职位, 说明: 1 班主任,2 讲师, 3 学工主管, 4 教研主管, 5 咨询师',entrydate date comment '入职时间',dept_id int unsigned comment '部门ID',salary int unsigned comment '月工资',create_time datetime not null comment '创建时间',update_time datetime not null comment '修改时间'
) comment '员工表';INSERT INTO tb_emp(id, username, password, name, gender, image, job, entrydate,dept_id,salary, create_time, update_time) VALUES(1,'jinyong','123456','金庸',1,'1.jpg',4,'2000-01-01',2,20000,now(),now()),(2,'zhangwuji','123456','张无忌',1,'2.jpg',2,'2015-01-01',2,18000,now(),now()),(3,'yangxiao','123456','杨逍',1,'3.jpg',2,'2008-05-01',2,16800,now(),now()),(4,'weiyixiao','123456','韦一笑',1,'4.jpg',2,'2007-01-01',2,12000,now(),now()),(5,'changyuchun','123456','常遇春',1,'5.jpg',2,'2012-12-05',2,9000,now(),now()),(6,'xiaozhao','123456','小昭',2,'6.jpg',3,'2013-09-05',1,6000,now(),now()),(7,'jixiaofu','123456','纪晓芙',2,'7.jpg',1,'2005-08-01',1,6500,now(),now()),(8,'zhouzhiruo','123456','周芷若',2,'8.jpg',1,'2014-11-09',1,7200,now(),now()),(9,'dingminjun','123456','丁敏君',2,'9.jpg',1,'2011-03-11',1,5300,now(),now()),(10,'zhaomin','123456','赵敏',2,'10.jpg',1,'2013-09-05',1,12000,now(),now()),(11,'luzhangke','123456','鹿杖客',1,'11.jpg',5,'2007-02-01',3,8900,now(),now()),(12,'hebiweng','123456','鹤笔翁',1,'12.jpg',5,'2008-08-18',3,7800,now(),now()),(13,'fangdongbai','123456','方东白',1,'13.jpg',5,'2012-11-01',3,6800,now(),now()),(14,'zhangsanfeng','123456','张三丰',1,'14.jpg',2,'2002-08-01',2,15800,now(),now()),(15,'yulianzhou','123456','俞莲舟',1,'15.jpg',2,'2011-05-01',2,11500,now(),now()),(16,'songyuanqiao','123456','宋远桥',1,'16.jpg',2,'2007-01-01',2,8300,now(),now()),(17,'chenyouliang','123456','陈友谅',1,'17.jpg',NULL,'2015-03-21',NULL,4500,now(),now());-- 薪资等级表
create table salgrade(grade int comment '等级',losal int comment '该等级最低薪资',hisal int comment '该等级最高薪资'
) comment '薪资等级表';insert into salgrade values (1,0,3000);
insert into salgrade values (2,3001,5000);
insert into salgrade values (3,5001,8000);
insert into salgrade values (4,8001,10000);
insert into salgrade values (5,10001,15000);
insert into salgrade values (6,15001,20000);
insert into salgrade values (7,20001,25000);
insert into salgrade values (8,25001,30000);

需求：

-- 1. 查询员工的姓名 , 及所属的部门名称 (隐式内连接实现)-- 2. 查询员工的姓名 , 及所属的部门名称 (显式内连接实现)-- 3. 查询员工的 姓名、性别、职位、部门名称 （隐式内连接）-- 4. 查询 薪资 高于 10000 的员工的姓名、性别、职位、部门名称（显式内连接）-- 5. 查询员工表 所有 员工的姓名, 和对应的部门名称 (左外连接)-- 6. 查询员工表 所有 员工的姓名, 和对应的部门名称 (右外连接)-- 7. 查询部门表 所有 部门的名称, 和对应的员工名称 (右外连接)-- 8. 查询 "教研部" 的所有员工信息 （标量子查询）-- 9. 查询在 "方东白" 入职之后的员工信息 （标量子查询）-- 10. 查询 "教研部" 和 "咨询部" 的所有员工信息 （列子查询）-- 11. 查询与 "韦一笑" 的入职日期 及 职位都相同的员工信息 （行子查询）-- 12. 查询入职日期是 "2006-01-01" 之后的员工信息 , 及其部门信息 （表子查询）-- 13. 查询 拥有员工的 部门ID、部门名称 (没有员工的部门无需展示)-- 14. 查询所有 在 2010-01-01 之后入职的员工, 及其归属的部门名称; 如果员工没有分配部门, 也需要展示出来-- 15. 查询 "教研部" 员工的平均工资-- 16. 查询工资比 "俞莲舟" 高的员工信息。-- 17. 查询 工资 比该企业员工的平均薪资 还要高的员工信息-- 18. 查询所有的部门信息, 并统计部门的员工人数-- 19. 查询所有员工的 姓名, 工资 , 及 工资等级 (有难度的哦)-- 20. 查询 "教研部" 所有员工的信息 及 工资等级 (有难度的哦)-- 21. 查询 工资 低于 本部门平均工资的员工信息 (有难度的哦)

作业2：多表查询

数据准备：

-- 分类表
create table category(id int unsigned primary key auto_increment comment '主键ID',name varchar(20) not null unique comment '分类名称',type tinyint unsigned not null comment '类型 1 菜品分类 2 套餐分类',sort tinyint unsigned not null comment '顺序',status tinyint unsigned not null default 0 comment '状态 0 禁用，1 启用',create_time datetime not null comment '创建时间',update_time datetime not null comment '更新时间'
) comment '分类' ;-- 菜品表
create table dish(id int unsigned primary key auto_increment comment '主键ID',name varchar(20) not null unique comment '菜品名称',category_id int unsigned not null comment '菜品分类ID',price decimal(8, 2) not null comment '菜品价格',image varchar(300) not null comment '菜品图片',description varchar(200) comment '描述信息',status tinyint unsigned not null default 0 comment '状态, 0 停售 1 起售',create_time datetime not null comment '创建时间',update_time datetime not null comment '更新时间'
) comment '菜品';-- 套餐表
create table setmeal(id int unsigned primary key auto_increment comment '主键ID',name varchar(20) not null unique comment '套餐名称',category_id int unsigned not null comment '分类id',price decimal(8, 2) not null comment '套餐价格',image varchar(300) not null comment '图片',description varchar(200) comment '描述信息',status tinyint unsigned not null default 0 comment '状态 0:停用 1:启用',create_time datetime not null comment '创建时间',update_time datetime not null comment '更新时间'
)comment '套餐' ;-- 套餐菜品关联表
create table setmeal_dish(id int unsigned primary key auto_increment comment '主键ID',setmeal_id int unsigned not null comment '套餐id ',dish_id int unsigned not null comment '菜品id',copies tinyint unsigned not null comment '份数'
)comment '套餐菜品中间表';-- ================================== 导入测试数据 ====================================
-- category
insert into category (id, type, name, sort, status, create_time, update_time) values (1, 1, '酒水饮料', 10, 1, '2022-08-09 22:09:18', '2022-08-09 22:09:18');
insert into category (id, type, name, sort, status, create_time, update_time) values (2, 1, '传统主食', 9, 1, '2022-08-09 22:09:32', '2022-08-09 22:18:53');
insert into category (id, type, name, sort, status, create_time, update_time) values (3, 2, '人气套餐', 12, 1, '2022-08-09 22:11:38', '2022-08-10 11:04:40');
insert into category (id, type, name, sort, status, create_time, update_time) values (4, 2, '商务套餐', 13, 1, '2022-08-09 22:14:10', '2022-08-10 11:04:48');
insert into category (id, type, name, sort, status, create_time, update_time) values (5, 1, '经典川菜', 6, 1, '2022-08-09 22:17:42', '2022-08-09 22:17:42');
insert into category (id, type, name, sort, status, create_time, update_time) values (6, 1, '新鲜时蔬', 7, 1, '2022-08-09 22:18:12', '2022-08-09 22:18:28');
insert into category (id, type, name, sort, status, create_time, update_time) values (7, 1, '汤类', 11, 1, '2022-08-10 10:51:47', '2022-08-10 10:51:47');-- dish
insert into dish (id, name, category_id, price, image, description, status, create_time, update_time) values (1,'王老吉', 1, 6.00, 'https://reggie-itcast.oss-cn-beijing.aliyuncs.com/41bfcacf-7ad4-4927-8b26-df366553a94c.png', '', 1, '2022-06-09 22:40:47', '2022-06-09 22:40:47');
insert into dish (id, name, category_id, price, image, description, status, create_time, update_time) values (2,'北冰洋', 1, 4.00, 'https://reggie-itcast.oss-cn-beijing.aliyuncs.com/4451d4be-89a2-4939-9c69-3a87151cb979.png', '还是小时候的味道', 1, '2022-06-10 09:18:49', '2022-06-10 09:18:49');
insert into dish (id, name, category_id, price, image, description, status, create_time, update_time) values (3,'雪花啤酒', 1, 4.00, 'https://reggie-itcast.oss-cn-beijing.aliyuncs.com/bf8cbfc1-04d2-40e8-9826-061ee41ab87c.png', '', 1, '2022-06-10 09:22:54', '2022-06-10 09:22:54');
insert into dish (id, name, category_id, price, image, description, status, create_time, update_time) values (4,'米饭', 2, 2.00, 'https://reggie-itcast.oss-cn-beijing.aliyuncs.com/76752350-2121-44d2-b477-10791c23a8ec.png', '精选五常大米', 1, '2022-06-10 09:30:17', '2022-06-10 09:30:17');
insert into dish (id, name, category_id, price, image, description, status, create_time, update_time) values (5,'馒头', 2, 1.00, 'https://reggie-itcast.oss-cn-beijing.aliyuncs.com/475cc599-8661-4899-8f9e-121dd8ef7d02.png', '优质面粉', 1, '2022-06-10 09:34:28', '2022-06-10 09:34:28');
insert into dish (id, name, category_id, price, image, description, status, create_time, update_time) values (6,'老坛酸菜鱼', 5, 56.00, 'https://reggie-itcast.oss-cn-beijing.aliyuncs.com/4a9cefba-6a74-467e-9fde-6e687ea725d7.png', '原料：汤，草鱼，酸菜', 1, '2022-06-10 09:40:51', '2022-06-10 09:40:51');
insert into dish (id, name, category_id, price, image, description, status, create_time, update_time) values (7,'经典酸菜鮰鱼', 5, 66.00, 'https://reggie-itcast.oss-cn-beijing.aliyuncs.com/5260ff39-986c-4a97-8850-2ec8c7583efc.png', '原料：酸菜，江团，鮰鱼', 1, '2022-06-10 09:46:02', '2022-06-10 09:46:02');
insert into dish (id, name, category_id, price, image, description, status, create_time, update_time) values (8,'蜀味水煮草鱼', 5, 38.00, 'https://reggie-itcast.oss-cn-beijing.aliyuncs.com/a6953d5a-4c18-4b30-9319-4926ee77261f.png', '原料：草鱼，汤', 1, '2022-06-10 09:48:37', '2022-06-10 09:48:37');
insert into dish (id, name, category_id, price, image, description, status, create_time, update_time) values (9,'清炒小油菜', 6, 18.00, 'https://reggie-itcast.oss-cn-beijing.aliyuncs.com/3613d38e-5614-41c2-90ed-ff175bf50716.png', '原料：小油菜', 1, '2022-06-10 09:51:46', '2022-06-10 09:51:46');
insert into dish (id, name, category_id, price, image, description, status, create_time, update_time) values (10,'蒜蓉娃娃菜', 6, 18.00, 'https://reggie-itcast.oss-cn-beijing.aliyuncs.com/4879ed66-3860-4b28-ba14-306ac025fdec.png', '原料：蒜，娃娃菜', 1, '2022-06-10 09:53:37', '2022-06-10 09:53:37');
insert into dish (id, name, category_id, price, image, description, status, create_time, update_time) values (11,'清炒西兰花', 6, 18.00, 'https://reggie-itcast.oss-cn-beijing.aliyuncs.com/e9ec4ba4-4b22-4fc8-9be0-4946e6aeb937.png', '原料：西兰花', 1, '2022-06-10 09:55:44', '2022-06-10 09:55:44');
insert into dish (id, name, category_id, price, image, description, status, create_time, update_time) values (12,'炝炒圆白菜', 6, 18.00, 'https://reggie-itcast.oss-cn-beijing.aliyuncs.com/22f59feb-0d44-430e-a6cd-6a49f27453ca.png', '原料：圆白菜', 1, '2022-06-10 09:58:35', '2022-06-10 09:58:35');
insert into dish (id, name, category_id, price, image, description, status, create_time, update_time) values (13,'清蒸鲈鱼', 5, 98.00, 'https://reggie-itcast.oss-cn-beijing.aliyuncs.com/c18b5c67-3b71-466c-a75a-e63c6449f21c.png', '原料：鲈鱼', 1, '2022-06-10 10:12:28', '2022-06-10 10:12:28');
insert into dish (id, name, category_id, price, image, description, status, create_time, update_time) values (14,'东坡肘子', 5, 138.00, 'https://reggie-itcast.oss-cn-beijing.aliyuncs.com/a80a4b8c-c93e-4f43-ac8a-856b0d5cc451.png', '原料：猪肘棒', 1, '2022-06-10 10:24:03', '2022-06-10 10:24:03');
insert into dish (id, name, category_id, price, image, description, status, create_time, update_time) values (15,'梅菜扣肉', 5, 58.00, 'https://reggie-itcast.oss-cn-beijing.aliyuncs.com/6080b118-e30a-4577-aab4-45042e3f88be.png', '原料：猪肉，梅菜', 1, '2022-06-10 10:26:03', '2022-06-10 10:26:03');
insert into dish (id, name, category_id, price, image, description, status, create_time, update_time) values (16,'剁椒鱼头', 5, 66.00, 'https://reggie-itcast.oss-cn-beijing.aliyuncs.com/13da832f-ef2c-484d-8370-5934a1045a06.png', '原料：鲢鱼，剁椒', 1, '2022-06-10 10:28:54', '2022-06-10 10:28:54');
insert into dish (id, name, category_id, price, image, description, status, create_time, update_time) values (17,'馋嘴牛蛙', 5, 98.00, 'https://reggie-itcast.oss-cn-beijing.aliyuncs.com/7a55b845-1f2b-41fa-9486-76d187ee9ee1.png', '配料：鲜活牛蛙，丝瓜，黄豆芽', 1, '2022-06-10 10:37:52', '2022-06-10 10:37:52');
insert into dish (id, name, category_id, price, image, description, status, create_time, update_time) values (18,'鸡蛋汤', 7, 4.00, 'https://reggie-itcast.oss-cn-beijing.aliyuncs.com/c09a0ee8-9d19-428d-81b9-746221824113.png', '配料：鸡蛋，紫菜', 1, '2022-06-10 10:54:25', '2022-06-10 10:54:25');
insert into dish (id, name, category_id, price, image, description, status, create_time, update_time) values (19,'平菇豆腐汤', 7, 6.00, 'https://reggie-itcast.oss-cn-beijing.aliyuncs.com/16d0a3d6-2253-4cfc-9b49-bf7bd9eb2ad2.png', '配料：豆腐，平菇', 1, '2022-06-10 10:55:02', '2022-06-10 10:55:02');-- setmeal
insert into setmeal (id, category_id, name, price, status, description, image, create_time, update_time) values (1, 4, '商务套餐A', 20.00, 1, '', 'https://reggie-itcast.oss-cn-beijing.aliyuncs.com/21a5ed3a-97f6-447a-af9d-53deabfb5661.png', '2022-06-10 10:58:09', '2022-06-10 10:58:09');
insert into setmeal (id, category_id, name, price, status, description, image, create_time, update_time) values (2, 4, '商务套餐B', 22.00, 1, '', 'https://reggie-itcast.oss-cn-beijing.aliyuncs.com/8d0075f8-9008-4390-94ca-2ca631440304.png', '2022-06-10 11:00:13', '2022-06-10 11:11:37');
insert into setmeal (id, category_id, name, price, status, description, image, create_time, update_time) values (3, 3, '人气套餐A', 49.00, 1, '', 'https://reggie-itcast.oss-cn-beijing.aliyuncs.com/8979566b-0e17-462b-81d8-8dbace4138f4.png', '2022-06-10 11:11:23', '2022-06-10 11:11:23');-- setmeal_dish
insert into setmeal_dish (id, setmeal_id, dish_id, copies) values (1, 1, 1, 1);
insert into setmeal_dish (id, setmeal_id, dish_id, copies) values (2, 1, 4, 1);
insert into setmeal_dish (id, setmeal_id, dish_id, copies) values (3, 1, 11, 1);
insert into setmeal_dish (id, setmeal_id, dish_id, copies) values (4, 2, 2, 1);
insert into setmeal_dish (id, setmeal_id, dish_id, copies) values (5, 2, 4, 1);
insert into setmeal_dish (id, setmeal_id, dish_id, copies) values (6, 2, 9, 1);
insert into setmeal_dish (id, setmeal_id, dish_id, copies) values (7, 3, 2, 1);
insert into setmeal_dish (id, setmeal_id, dish_id, copies) values (8, 3, 6, 1);
insert into setmeal_dish (id, setmeal_id, dish_id, copies) values (9, 3, 5, 1);

需求：


-- 1. 查询价格低于 20元 且 状态为 '起售' 的菜品的名称 、价格 及其 菜品的分类名称 .-- 2. 查询所有价格在 40元(含)到100元(含)之间 且 状态为'起售'的菜品名称、价格 及其 菜品的分类名称 (即使菜品没有分类 , 也需要将菜品查询出来).-- 3. 查询每个分类下最便宜的菜品, 展示出分类的名称、便宜的菜品的价格 .-- 4. 查询各个分类下 状态为 '起售' , 并且 该分类下菜品总数量大于等于2 的 分类名称 .-- 5. 查询出 "商务套餐A" 中包含了哪些菜品 （展示出套餐名称、价格, 套餐包含的菜品名称、价格、份数）.-- 6. 查询哪些套餐中包含的有 "米饭"  (展示出套餐名称、套餐价格、套餐分类名称).-- 7. 查询出 低于 菜品平均价格的菜品信息 (展示出菜品名称、菜品价格、菜品分类名称).-- 8. 查询出与 "剁椒鱼头" 的分类 及 价格都相同的菜品数据 .

作业3：基于SpringBoot整合Mybatis的形式完成数据查询操作

需求：

1. 新建一个数据库 mybatis_homework，将下面的表结构及测试数据导入数据库中。
2. 创建SpringBoot项目，勾选 mybatis、mysql 驱动的相关依赖。
3. 定义实体类 Emp ，定义EmpMapper接口。
4. 编写 application.properties，在其中配置数据库连接信息。
5. 完成查询 Emp 全部数据的操作。
6. 编写单元测试进行测试。

数据库：

-- 员工表
create table emp (id int unsigned primary key auto_increment comment 'ID',username varchar(20) not null unique comment '用户名',password varchar(32) default '123456' comment '密码',name varchar(10) not null comment '姓名',gender tinyint unsigned not null comment '性别, 说明: 1 男, 2 女',image varchar(300) comment '图像',job tinyint unsigned comment '职位, 说明: 1 班主任,2 讲师, 3 学工主管, 4 教研主管'
) comment '员工表';INSERT INTO emp (id, username, password, name, gender, image, job) VALUES(1,'jinyong','123456','金庸',1,'1.jpg',4),(2,'zhangwuji','123456','张无忌',1,'2.jpg',2),(3,'yangxiao','123456','杨逍',1,'3.jpg',2),(4,'weiyixiao','123456','韦一笑',1,'4.jpg',2),(5,'changyuchun','123456','常遇春',1,'5.jpg',2),(6,'xiaozhao','123456','小昭',2,'6.jpg',3),(7,'jixiaofu','123456','纪晓芙',2,'7.jpg',1),(8,'zhouzhiruo','123456','周芷若',2,'8.jpg',1),(9,'dingminjun','123456','丁敏君',2,'9.jpg',1),(10,'zhaomin','123456','赵敏',2,'10.jpg',1),(11,'luzhangke','123456','鹿杖客',1,'11.jpg',5);