Select cast(DATEPART(week, cast(Left(Ltrim(current_week), 10)as date)) as nvarchar) +'~~'+cast(DATEPART(week, cast(right(Rtrim(current_week), 10)as date))as nvarchar) as [Week Number] from #mytable

Week Number

8~~9

3~~4

3~~4

3~~4

4~~5

5~~6

7~~8

7~~8

This will show on which week the begin and end dates will fall in that calendar year. If you just need to find the week that that falls in the range of dates you provided then it will be necessary to know on what date your week actually starts. LTRIM and RTRIM will not actually be necessary if your sample did not contain SPACE. Hope this helps.