SQL group by frequency within a date range

Question

I have a requirement to write a stored procedure that accepts a start date, end date and a frequency (day, week, month, quarter, year) and outputs a result set based on thos

Answer 1

Something like this should work.

select date_column,
     sum(count)
from @table
where date_column between @start_date and @end_date
group by case @frequency
                    when 'week' then datepart(week,date_column )
                    when 'year' then datepart(year,date_column)
                    when 'quarter' then datepart(quarter,date_column)
                    when ...
         end;