INNER JOIN

This lesson uses the unmodified DDI_SQL_Training dataset v1.0.0 on SQL Server 2019 or later. Return rows whose keys match in both related tables.

Run the example

SELECT TOP (5) p.ProductID, p.ProductName, c.CategoryName
FROM dbo.Products AS p
INNER JOIN dbo.Categories AS c ON c.CategoryID = p.CategoryID
ORDER BY p.ProductID;

Read it step by step

1. Products.CategoryID references the Categories primary key.
2. INNER JOIN retains product rows with a matching category.
3. ORDER BY ProductID selects five predictable products from the joined set.

Check the result

All canonical products have a category because the foreign key requires it.

Practice

Show OrderID, CustomerID, and FirstName for Orders 1 through 3.

SELECT o.OrderID, o.CustomerID, c.FirstName
FROM dbo.Orders AS o
INNER JOIN dbo.Customers AS c ON c.CustomerID = o.CustomerID
WHERE o.OrderID BETWEEN 1 AND 3
ORDER BY o.OrderID;