SQL Server Interview Question #62

What is an INNER JOIN?

Joins, Subqueries, CTEs & Set Operators Mid-Level Intermediate

Quick Interview Answer

INNER JOIN returns only rows for which the join predicate finds a match on both sides. For example, if Products.CategoryId references Categories.Id, an INNER JOIN returns products that have matching category rows. Rows without a matching counterpart are excluded from the result.

Detailed Explanation

INNER JOIN returns only rows for which the join predicate finds a match on both sides.

For example, if Products.CategoryId references Categories.Id, an INNER JOIN returns products that have matching category rows. Rows without a matching counterpart are excluded from the result.

Code Example

SELECT p.Id, p.Name, c.Name AS CategoryName
FROM dbo.Products AS p
INNER JOIN dbo.Categories AS c
    ON p.CategoryId = c.Id;