SQL Server 2017

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CREATE TABLE products (
idProduct INTEGER NOT NULL ,
title NVARCHAR(255) UNIQUE NOT NULL,
measurement_unit NVARCHAR(77) NOT NULL ,
PRIMARY KEY(idProduct));

-- поменять данные на свои
INSERT INTO products VALUES (1, 'Product 1', N'кг');
-- смотрим, что вставилось
SELECT * FROM products;


idProduct
title
measurement_unit


1
Product 1
кг


CREATE TABLE providers (
idProvider INTEGER NOT NULL ,
title NVARCHAR(77) NOT NULL UNIQUE,
some_address NVARCHAR(77),
phone INTEGER NOT NULL,
PRIMARY KEY(idProvider));

-- вставить данные
CREATE TABLE sales (
idSale INTEGER NOT NULL ,
Product_idProduct INTEGER NOT NULL ,
sale_date DATE DEFAULT GETDATE(),
price INTEGER NOT NULL,
count INTEGER NOT NULL,
PRIMARY KEY(idSale),
FOREIGN KEY(Product_idProduct)
REFERENCES products(idProduct));

-- вставить данные
CREATE TABLE purchases (
idPurchase INTEGER NOT NULL ,
Product_idProduct INTEGER NOT NULL ,
Provider_idProvider INTEGER NOT NULL ,
count INTEGER NOT NULL,
purchase_date DATE ,
price INTEGER ,
PRIMARY KEY(idPurchase) ,
FOREIGN KEY(Provider_idProvider)
REFERENCES providers(idProvider),
FOREIGN KEY(Product_idProduct)
REFERENCES products(idProduct));

-- вставить данные