第一次作业

CREATE DATABASE mydb6_product;3USE mydb6_product;
USE mydb6_product;

CREATE TABLE employees (
id INT PRIMARY KEY
name VARCHAR(5O) NOT NULL,
age INT,gender VARCHAR(1G) NOT NULL DEFAULT 'unknown',
salary FLOAT
)ENGINE=InnoDB;

CREATE TABLE orders（
id INT PRIMARY KEY,
name VARCHAR(100) NOT NULL,
price FLOAT,
quantity INT,
category VARCHAR(50)
)ENGINE=InnoDB;

CREATE TABLE invoices(
nUmber INT AUTO_INCREMENT PRIMARY KEY.order_id INT,
in_date DATE,
total_amount FLOAT,
CHECK (total_amount > 0),
FOREIGN KEY (order_id)REFERENCES orders(id)
)ENGINE=InnoDB;