sql server - Sql convert string of numbers to int -

i want select either week days or full week depending on parameter.

i looking @ using case statement following, don't know how convert string of number value can passed integers.

im doing wrong appreciated.

this im setting param value:

set @days = (select case when fullweek = 1 cast('1,2,3,4,5,6,7' numeric(38,0))                         when fullweek = 0 cast('2, 3,4,5,6' numeric(38,0)) end              reports) 

and how want call this, part of statement:

where datepart(dw,date) in (@days) 

why not simplify , way:

where (fullweek = 1) -- days of week    or        (fullweek = 0 , datepart(dw,date) in (2,3,4,5,6))