Transact SQL :: Load Data For Last 15 Days By Decrementing Current Date And While Loop

I have a dynamic sql query where in I am comparing two tables and loading data for last 15 days. e.g today 2050921 then I am going to load till 20150906.

I pass on 2 variables @currentdate and @currentdate-1 to the query which are in date format 'yyyymmdd'

I need to do this for last 15 days how do I do this using while loop.

Note my date format is YYYYMMDD.

DECLARE @SQL VARCHAR(MAX)
@sql = ' insert into target 
select from table_1_currentdate a
LEFT JOIN Table_2_currentdate-1 b
on a.col1=b.col1  where b.col1 is null '

exec(@sql)

I have to use while loop and decrement it every time and load data for last 15 days comparing two tables. I tried so many times I am not getting it right .