Why should you care?

Shoppers abandon slow catalogs; overselling destroys trust.

See it live — copy this example

Run in SQL Server Management Studio (SSMS) or Azure Data Studio.

USE DataVerse;
IF OBJECT_ID(N'dbo.OrderItems', N'U') IS NULL
CREATE TABLE dbo.OrderItems (
    OrderItemId INT IDENTITY PRIMARY KEY,
    OrderId INT NOT NULL REFERENCES dbo.Orders(OrderId),
    ProductId INT NOT NULL REFERENCES dbo.Products(ProductId),
    Qty INT NOT NULL CHECK (Qty > 0),
    UnitPrice DECIMAL(10,2) NOT NULL
);
SELECT p.Name, SUM(oi.Qty) AS UnitsSold, SUM(oi.Qty * oi.UnitPrice) AS Gross
FROM dbo.OrderItems oi
JOIN dbo.Products p ON p.ProductId = oi.ProductId
GROUP BY p.Name
ORDER BY Gross DESC;

What happened?

• OrderItems lines capture what sold.
• The aggregate ranks products by gross — a merchant dashboard staple.

Practice next

1. Ensure Products, Orders, OrderItems exist.
2. Insert sample lines and run the ranking query.
3. Add a UNIQUE (OrderId, ProductId) if your rules need it.
4. Top 5 products by UnitsSold.
5. Filter Gross > 10000 with HAVING.

Remember

Products + orders + lines + stock. Index catalog filters. Transactional checkout.

DataVerse shop analytics

Merchants see best sellers from OrderItems.

Outcome: Inventory planning follows real demand.