Hi,
Here's one of the possible solution.
-- # of guests the hotel served on each day in December 2012
SELECT g.checkin AS [date], COUNT(*) AS [#of_guests_served]
FROM dbo.guests g
WHERE g.checkin BETWEEN CAST('20120101' AS datetime) AND CAST('20121231' AS datetime)
GROUP BY g.checkin;
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Hai Ton
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