1.数据库表
# 创建用户表
create table user(
userId int primary key auto_increment,
username varchar(20) not null,
password varchar(18) not null,
address varchar(100),
phone varchar(11)
);
#创建分类表
create table category(
cid varchar(32) PRIMARY KEY ,
cname varchar(100) not null #分类名称
);
# 商品表
CREATE TABLE `products` (
`pid` varchar(32) PRIMARY KEY,
`name` VARCHAR(40) ,
`price` DOUBLE(7,2),
category_id varchar(32),
constraint fk_products_category_id foreign key(category_id) references category(cid)
);
#订单表
create table `orders`(
`oid` varchar(32) PRIMARY KEY ,
`totalprice` double(12,2), #总计
`userId` int,
constraint fk_orders_userId foreign key(userId) references user(userId) #外键
);
# 订单项表
create table orderitem(
oid varchar(32), #订单id
pid varchar(32), #商品id
num int , #购买商品数量
primary key(oid,pid), #主键
constraint fk_orderitem_oid foreign key(oid) references orders(oid),
constraint fk_orderitem_pid foreign key(pid) references products(pid)
);
#-----------------------------------------------
#初始化数据
#用户表添加数据
INSERT INTO USER(username,PASSWORD,address,phone) VALUES('张三','123','北京昌平沙河','13812345678');
INSERT INTO USER(username,PASSWORD,address,phone) VALUES('王五','5678','北京海淀','13812345141');
INSERT INTO USER(username,PASSWORD,address,phone) VALUES('赵六','123','北京朝阳','13812340987');
INSERT INTO USER(username,PASSWORD,address,phone) VALUES('田七','123','北京大兴','13812345687');
#给分类表初始化数据
insert into category values('c001','电器');
insert into category values('c002','服饰');
insert into category values('c003','化妆品');
insert into category values('c004','书籍');
#给商品表初始化数据
insert into products(pid,name,price,category_id) values('p001','联想',5000,'c001');
insert into products(pid,name,price,category_id) values('p002','海尔',3000,'c001');
insert into products(pid,name,price,category_id) values('p003','雷神',5000,'c001');
insert into products(pid,name,price,category_id) values('p004','JACK JONES',800,'c002');
insert into products(pid,name,price,category_id) values('p005','真维斯',200,'c002');
insert into products(pid,name,price,category_id) values('p006','花花公子',440,'c002');
insert into products(pid,name,price,category_id) values('p007','劲霸',2000,'c002');
insert into products(pid,name,price,category_id) values('p008','香奈儿',800,'c003');
insert into products(pid,name,price,category_id) values('p009','相宜本草',200,'c003');
insert into products(pid,name,price,category_id) values('p010','梅明子',200,null);
#添加订单
insert into orders values('o6100',18000.50,1);
insert into orders values('o6101',7200.35,1);
insert into orders values('o6102',600.00,2);
insert into orders values('o6103',1300.26,4);
#订单详情表
insert into orderitem values('o6100','p001',1),('o6100','p002',1),('o6101','p003',1);
2.多表查询
2.1查询所有用户的订单
SELECT o.oid,o.totalprice, u.userId,u.username,u.phone
FROM orders o INNER JOIN USER u ON o.userId=u.userId;
2.2查询用户id为 1 的所有订单详情
SELECT o.oid,o.totalprice, u.userId,u.username,u.phone ,oi.pid
FROM orders o INNER JOIN USER u ON o.userId=u.userId
INNER JOIN orderitem oi ON o.oid=oi.oid
where u.userid=1;
3.子查询
3.1查看用户为张三的订单
SELECT * FROM orders WHERE userId=(SELECT userid FROM USER WHERE username='张三');
3.2查询出订单的价格大于800的所有用户信息
SELECT * FROM USER WHERE userId IN (SELECT DISTINCT userId FROM orders WHERE totalprice>800);
4.分页查询
#查询所有订单信息，每页显示5条数据
#查询第一页
SELECT * FROM orders LIMIT 0,5;
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