php: Get start date of week using datepart

lundi 29 juin 2015

I have a table with 2 columns - Date, ItemsSold. I have the following query

Select datepart(week, [Date]) as WeekNo, SUM([ItemsSold]) as Total From [table] 
group by datepart(week, [Date])

This gives the following output

WeekNo   Total
3         20
4         30

What I actually need is an output as follows

WeekOf          Total
11 Jan 2015      20
18 Jan 2015      30

How do I get the start date of the week that datepart returns?

php