要求：
每个表的主外键
客户的姓名不能为空值
邮箱不能重复
客户的性别(男，女)
商品goods(商品编号goods_ id，商品名goods_ name, 单价unitprice, 商品类别category, 供应商provider)
create table goods(
goods_id tinyint primary key auto_increment ,
goos_name varchar(100) not null default ' ',
unitprice decimal (10,2) not null default 0,
category smallint not null default 0,
provider varchar(30) not null default ' '
);
desc goods;
+-----------+------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------+------------------+------+-----+---------+-------+
| goods_id | int(10) unsigned | NO | PRI | NULL | |
| goos_name | varchar(100) | NO | | | |
| unitprice | decimal(10,2) | NO | | 0.00 | |
| category | smallint(6) | NO | | 0 | |
| provider | varchar(30) | NO | | | |
+-----------+------------------+------+-----+---------+-------+
5 rows in set (0.01 sec)
客户customer(客户号customer_ id,姓名name,住址address,邮箱email,性别sex，身份证card_id)
create table customer(
customer_id int unsigned primary key auto_increment,
name varchar(100) not null default ' ',
address varchar(100) not null default ' ',
email varchar(30) not null unique,
sex char(2) not null default '男',
card_id varchar(20) not null unique
);
desc custome;
+-------------+------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------------+------------------+------+-----+---------+----------------+
| customer_id | int(10) unsigned | NO | PRI | NULL | auto_increment |
| name | varchar(100) | NO | | | |
| address | varchar(100) | NO | | | |
| email | varchar(30) | NO | UNI | NULL | |
| sex | char(2) | NO | | 男 | |
| card_id | varchar(20) | NO | UNI | NULL | |
+-------------+------------------+------+-----+---------+----------------+
6 rows in set (0.08 sec)
购买purchase(购买订单号order_ id,客户号customer_ id,商品号goods_ id,购买数量nums)
create table purchase(
order_id varchar(30) not null primary key,
customer_id int unsigned,
goods_id int unsigned,
num int not null default 0,
foreign key(customer_id) references customer(customer_id),
foreign key(goods_id) references goods(goods_id)
);
desc purchase;
+-------------+------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------------+------------------+------+-----+---------+-------+
| order_id | varchar(30) | NO | PRI | NULL | |
| customer_id | int(10) unsigned | YES | MUL | NULL | |
| goods_id | int(10) unsigned | YES | MUL | NULL | |
| num | int(11) | NO | | 0 | |
+-------------+------------------+------+-----+---------+-------+
4 rows in set (0.00 sec)