SQL Server Interview Question #87

Can GROUP BY use multiple columns?

Aggregate Functions, GROUP BY & Window Functions Mid-Level Intermediate

Detailed Explanation

Yes. GROUP BY can contain multiple expressions. Each unique combination of the grouping values forms a separate group.

For example, grouping orders by year and month produces one aggregate row for each year/month combination. Multiple-column grouping is common in dashboard and reporting queries.

Code Example

SELECT YEAR(OrderDate) AS OrderYear,
       MONTH(OrderDate) AS OrderMonth,
       COUNT(*) AS OrderCount,
       SUM(TotalAmount) AS Sales
FROM dbo.Orders
GROUP BY YEAR(OrderDate), MONTH(OrderDate)
ORDER BY OrderYear, OrderMonth;