二手商品交易数据库sql语句

以下是一个简单的二手商品交易数据库的 SQL 语句，包含商品信息、用户信息和交易记录：

创建商品信息表：

CREATE TABLE products (
    product_id INT PRIMARY KEY,
    name VARCHAR(50) NOT NULL,
    price DECIMAL(10, 2) NOT NULL,
    description TEXT,
    seller_id INT NOT NULL,
    FOREIGN KEY (seller_id) REFERENCES users (user_id)
);

创建用户信息表：

CREATE TABLE users (
    user_id INT PRIMARY KEY,
    username VARCHAR(50) NOT NULL,
    email VARCHAR(100) NOT NULL,
    password VARCHAR(50) NOT NULL
);

创建交易记录表：

CREATE TABLE transactions (
    transaction_id INT PRIMARY KEY,
    buyer_id INT NOT NULL,
    seller_id INT NOT NULL,
    product_id INT NOT NULL,
    price DECIMAL(10, 2) NOT NULL,
    transaction_date TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    FOREIGN KEY (buyer_id) REFERENCES users (user_id),
    FOREIGN KEY (seller_id) REFERENCES users (user_id),
    FOREIGN KEY (product_id) REFERENCES products (product_id)
);

插入商品信息：

INSERT INTO products (product_id, name, price, description, seller_id)
VALUES (1, 'iPhone X', 999.99, '64GB, space grey', 1);

INSERT INTO products (product_id, name, price, description, seller_id)
VALUES (2, 'AirPods', 149.99, 'Wireless earbuds', 2);

INSERT INTO products (product_id, name, price, description, seller_id)
VALUES (3, 'Nintendo Switch', 299.99, 'Console with Joy-Cons', 3);

插入用户信息：

INSERT INTO users (user_id, username, email, password)
VALUES (1, 'john', 'john@example.com', 'password123');

INSERT INTO users (user_id, username, email, password)
VALUES (2, 'jane', 'jane@example.com', 'password456');

INSERT INTO users (user_id, username, email, password)
VALUES (3, 'bob', 'bob@example.com', 'password789');

插入交易记录：

INSERT INTO transactions (transaction_id, buyer_id, seller_id, product_id, price)
VALUES (1, 2, 1, 1, 999.99);

INSERT INTO transactions (transaction_id, buyer_id, seller_id, product_id, price)
VALUES (2, 3, 1, 2, 149.99);

INSERT INTO transactions (transaction_id, buyer_id, seller_id, product_id, price)
VALUES (3, 1, 3, 3, 299.99);

以上只是一个简单的示例，实际的二手交易数据库可能需要更多的表和字段，以及更复杂的查询和操作。