insert into MyTable <список полей>
select <список>
select  @id = IDENT_CURRENT('MyTable')

<skipped>
<skipped>
<skipped>

update MyTable set поле1 = значение1,
                             поле2=значеие2
where ID = @id 

if @@rowcount<>1 
ОШИБКА 

create table #t(id int not null identity, f int not null)

declare @id int
declare @t table(id int not null)



insert #t(f)
output inserted.id 
into @t(id)
select 1

select @id = id
from @t


select @id 

drop table #t 

create table t (id int identity, f int ) 

declare @t table (id int identity(2,2), inserted_id int )

insert t 
output inserted.id
into @t(inserted_id)
select 1 

select [SCOPE_IDENTITY] = SCOPE_IDENTITY()
select * from @t


drop table t