a unsuccessful insert will not change @@identity

create table #dsfdsf(a varchar(1000),b int identity)

insert into #dsfdsf(a)

select 'gfdfg' df

select  @@identity

insert into #dsfdsf(a)

select 'gfdfg' df

where 1=5  

select  @@identity

drop table #dsfdsf

the select returns 1 in both cases