-- 02_create_tables.sql
-- Скрипт для создания таблиц

USE [AdoNetShop];
GO

-- Таблица Categories
IF NOT EXISTS (SELECT * FROM sys.tables WHERE name = 'Categories')
BEGIN
    CREATE TABLE Categories (
        Id INT IDENTITY(1,1) PRIMARY KEY,
        Name NVARCHAR(100) NOT NULL
    );
END
GO

-- Таблица Products
IF NOT EXISTS (SELECT * FROM sys.tables WHERE name = 'Products')
BEGIN
    CREATE TABLE Products (
        Id INT IDENTITY(1,1) PRIMARY KEY,
        Name NVARCHAR(200) NOT NULL,
        Description NVARCHAR(MAX) NULL,
        Price DECIMAL(18, 2) NOT NULL CHECK (Price > 0),
        StockQuantity INT NOT NULL DEFAULT 0 CHECK (StockQuantity >= 0),
        CategoryId INT NOT NULL,
        FOREIGN KEY (CategoryId) REFERENCES Categories(Id)
    );
END
GO

-- Таблица Customers
IF NOT EXISTS (SELECT * FROM sys.tables WHERE name = 'Customers')
BEGIN
    CREATE TABLE Customers (
        Id INT IDENTITY(1,1) PRIMARY KEY,
        Name NVARCHAR(100) NOT NULL,
        Email NVARCHAR(100) NOT NULL UNIQUE,
        Phone NVARCHAR(20) NULL
    );
END
GO

-- Таблица Orders
IF NOT EXISTS (SELECT * FROM sys.tables WHERE name = 'Orders')
BEGIN
    CREATE TABLE Orders (
        Id INT IDENTITY(1,1) PRIMARY KEY,
        CustomerId INT NOT NULL,
        OrderDate DATETIME2 NOT NULL DEFAULT GETDATE(),
        Status NVARCHAR(50) NOT NULL DEFAULT 'New',
        TotalAmount DECIMAL(18, 2) NOT NULL DEFAULT 0 CHECK (TotalAmount >= 0),
        FOREIGN KEY (CustomerId) REFERENCES Customers(Id)
    );
END
GO

-- Таблица OrderItems
IF NOT EXISTS (SELECT * FROM sys.tables WHERE name = 'OrderItems')
BEGIN
    CREATE TABLE OrderItems (
        Id INT IDENTITY(1,1) PRIMARY KEY,
        OrderId INT NOT NULL,
        ProductId INT NOT NULL,
        Quantity INT NOT NULL CHECK (Quantity > 0),
        Price DECIMAL(18, 2) NOT NULL CHECK (Price > 0),
        FOREIGN KEY (OrderId) REFERENCES Orders(Id) ON DELETE CASCADE,
        FOREIGN KEY (ProductId) REFERENCES Products(Id)
    );
END
GO

-- Индексы для внешних ключей (улучшают производительность JOIN'ов)
IF NOT EXISTS (SELECT * FROM sys.indexes WHERE name = 'IX_Products_CategoryId')
    CREATE INDEX IX_Products_CategoryId ON Products(CategoryId);

IF NOT EXISTS (SELECT * FROM sys.indexes WHERE name = 'IX_Orders_CustomerId')
    CREATE INDEX IX_Orders_CustomerId ON Orders(CustomerId);

IF NOT EXISTS (SELECT * FROM sys.indexes WHERE name = 'IX_OrderItems_OrderId')
    CREATE INDEX IX_OrderItems_OrderId ON OrderItems(OrderId);

IF NOT EXISTS (SELECT * FROM sys.indexes WHERE name = 'IX_OrderItems_ProductId')
    CREATE INDEX IX_OrderItems_ProductId ON OrderItems(ProductId);
GO