Case statement in where clause

[janetb]

I need to do something like the following where the case statement is in the where clause? Any ideas?

select v.chartID, max(rs1.dateService) as dateService from myTable v,
(select distinct dateService, chartID from myTable where (datePart(year,dateService)=@yr and datePart(month,dateService)=@mon) and (procedureKey='90657' or procedureKey='90658')) as rs1
where (v.chartID=rs1.chartID) and (v.procedureKey='90657' or v.procedureKey='90658') and (
(case when @mon=1 then dateDiff(day,v.dateService,@myDate)< 216
when @mon=2 then dateDiff(day,v.dateService,@myDate)<244
when @mon=3 then dateDiff(day,v.dateService,@myDate)<275
when @mon=4 then dateDiff(day,v.dateService,@myDate)<305
when @mon=5 then dateDiff(day,v.dateService,@myDate)<336
when @mon=6 then dateDiff(day,v.dateService,@myDate)<366
when @mon=7 then dateDiff(day,v.dateService,@myDate)<32
when @mon=8 then dateDiff(day,v.dateService,@myDate)<63
when @mon=9 then dateDiff(day,v.dateService,@myDate)<93
when @mon=10 then dateDiff(day,v.dateService,@myDate)<124
when @mon=11 then dateDiff(day,v.dateService,@myDate)<154
when @mon=12 then dateDiff(day,v.dateService,@myDate)<185
end)
group by v.chartID, rs1.procedureKey

[janetb]

Went with this, but is there a way to do in where clause?

DECLARE
@mycheck int
IF @mon=1
set @mycheck = 216
else if @mon=2
set @mycheck = 244
.....
where
....

dateDiff(day,v.dateService,@myDate) < @mycheck