⟩ How To Count Groups Returned with the GROUP BY Clause in MS SQL Server?
If you use the COUNT(*) function on groups returned with the GROUP BY clause, it will count the number of rows within each group, not the number of groups. If you want to count the number of groups, you can put the GROUP BY query into a subquery and apply the COUNT(*) function on the main query as shown in the following tutorial exercise:
SELECT tag AS Category, YEAR(created) AS Year,
COUNT(*) AS Counts FROM ggl_links GROUP BY tag,
YEAR(created)
GO
Category Year Counts
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JOBS 2007 1
SELECT COUNT(*) FROM (
SELECT tag AS Category, YEAR(created) AS Year,
COUNT(*) AS Counts FROM ggl_links GROUP BY tag,
YEAR(created) ) groups
GO
7