新建产品库
mysql> CREATE DATABASE mydb6_product;
使用产品库
mysql> USE mydb6_product;
创建employess表
mysql> CREATE TABLE employees (
-> id INT PRIMARY KEY,
-> name VARCHAR(50) NOT NULL,
-> age INT,
-> gender VARCHAR(10) NOT NULL DEFAULT 'unknown',
-> salary FLOAT
-> );
创建orders表
mysql> CREATE TABLE orders (
-> id INT PRIMARY KEY,
-> name VARCHAR(100) NOT NULL,
-> price FLOAT,
-> quantity INT,
-> category VARCHAR(50)
-> );
创建involces表
mysql> 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)
-> );
