How To Make @str Global?

If following code, it is ok if I execute part1 and q1 together.
but if I try to execute Q2, I got error

Server: Msg 137, Level 15, State 2, Line 4
Must declare the variable '@str'.

I guess I have to execute part1 and Q2 at same time.

Is there a way to avoid that. I mean after I execute part1 @str will be kept in memory, and I can execut q2 without a problem? (like in SAS)
Thank

/* Part1*/
/* how to make @str global*/
declare @str nvarchar(20);
set @str='%subway%';

/*Q1*/
select *, case regionname when 'telesales' then 't' else 'o' end as rn
from dbo.RPT_ContractDetails
where businessname like @str

/* Q2*/
select contracttypename,regionname, count(*)as cou, sum(fundingamount)as Dollar
from dbo.RPT_ContractDetails
where businessname like @str
group by contracttypename,regionname