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

select `date` as weekOf, sum(amt)
from myTable
where `date` between '2011-10-01' and '2012-01-01'
group by week(`date` )