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

 Create procedure MyProc
 @startDate DateTime,
 @endDate DateTime,
 @freq varChar(5)
 As

    If @freq = "day" 
        Select DateAdd(day, 0, datediff(day, 0, date)), Frequency,
        Sum(Count) 
        From Table
        Group By DateAdd(day, 0, datediff(day, 0, date))
    Else If @freq = "week" 
        Select DateAdd(week, 0, datediff(week, 0, date)), Frequency,
        Sum(Count) 
        From Table
        Group By DateAdd(week, 0, datediff(week, 0, date))
    Else If @freq = "Month" 
        Select DateAdd(Month, 0, datediff(Month, 0, date)), Frequency,
        Sum(Count) 
        From Table
        Group By DateAdd(Month, 0, datediff(Month, 0, date))
    Else If @freq = "Quarter" 
        Select DateAdd(Quarter, 0, datediff(Quarter, 0, date)), Frequency,
        Sum(Count) 
        From Table
        Group By DateAdd(Quarter, 0, datediff(Quarter, 0, date))
    Else If @freq = "Year" 
        Select DateAdd(Year, 0, datediff(Year, 0, date)), Frequency,
        Sum(Count) 
        From Table
        Group By DateAdd(Year, 0, datediff(Year, 0, date))