Why can't I get the @@rowcount value?

Question

Below is a simplified version of SQL script I have. print @RowNum always shows 0, rather than the real record number of the first result set. What's wrong? Thank you.

declare @i int, @RowNum int
set @i=0
while @i<2
begin
    execute StoredProcedure @i --containing a big select
    if @i=0 set @RowNum=@@rowcount
    set @i=@i+1
end
print @RowNum

Answer 1

because this if @i=0

sets it to 0, even a print statement will set it to 0

now run this

declare @i int, @RowNum int
set @i=0
while @i<2
begin
    if @i=0
    begin   
        execute StoredProcedure @i --containing a big select
        set @RowNum=@@rowcount
    end
    else
    execute StoredProcedure @i 
    set @i=@i+1
end
print @RowNum

here is another example

select 1
union all
select 2

select @@rowcount --2
go

now it will be 0

select 1
union all
select 2
if 1=1
select @@rowcount --0

PRINT also messes it up, this will be 2

select 1
union all
select 2

select @@rowcount --2
go

this will be 0

select 1
union all
select 2

print '1'
select @@rowcount -- 0

I created a post with more examples and explanations here: When should you store @@ROWCOUNT into a variable?