GROUP BY with multiple columns

ASA SQL User's Guide
Summarizing, Grouping and Sorting Query Results
Understanding GROUP BY

GROUP BY with multiple columns

You can list more than one expression in the GROUP BY clause in order to nest groups—that is, you can group a table by any combination of expressions.

The following query lists the average price of products, grouped first by name and then by size:

SELECT name, size, AVG(unit_price)
FROM product
GROUP BY name, size

name	size	AVG(product.unit_price)
Tee Shirt	Small	9
Tee Shirt	Medium	14
Tee Shirt	One size fits all	14
Baseball Cap	One size fits all	9.5
...	...	...

Columns in GROUP BY that are not in the select list

A Sybase extension to the SQL/92 standard that is supported by both Adaptive Server Enterprise and Adaptive Server Anywhere is to allow expressions to the GROUP BY clause that are not in the select list. For example, the following query lists the number of contacts in each city:

SELECT state, count(id)
FROM contact
GROUP BY state, city