GROUP BY

This lesson uses the unmodified DDI_SQL_Training dataset v1.0.0 on SQL Server 2019 or later. Count customers within each region.

Run the example

SELECT Region, COUNT(*) AS CustomerCount
FROM dbo.Customers
GROUP BY Region
ORDER BY Region;

Read it step by step

1. GROUP BY Region forms one group for each distinct Region value.
2. COUNT(*) counts customer rows in each group.
3. ORDER BY Region sorts the summary rows; grouping alone promises no output order.

Check the result

The counts add up to all 20 customers.

Practice

Count customers in each City and display cities alphabetically.

SELECT City, COUNT(*) AS CustomerCount
FROM dbo.Customers
GROUP BY City
ORDER BY City;