How can I create a row for values that don't exist and fill the count with 0 values?

Question

In SQL Server, I\'m running a query on users age groups on data where, for some years, there are zero users per age group. For example there were users in 2013 in the \"18-21\"

Answer 1

Try This...

SELECT YEAR, AGE_GROUP, isnull(Sum(USERS),0) as usercount,
FROM USERS
 WHERE YEAR = '2013'
AND PRIMARY_GROUP = 'NT'
GROUP BY YEAR, AGE_GROUP