row_number()over(order by nop)-row_number()over(partition by uh order by nop)

with any_t (nop, op, nv, uh) as (
select * from (values 
(05, 'отрезка',  2.5, 'заготовительный'),
(10, 'очистка',  2.1, 'заготовительный'),
(15, 'сверление', 2.5,' механический'),
(20, 'слесарная', 1.1, 'заготовительный')
)v(a,b,c,d)
)
select max(nop) as x_nop
     , sum(nv) as total_nv
	 , uh
  from 
  (
     select * , row_number() over(order by nop) - row_number() over(partition by uh order by nop) as x_group_id
      from any_t
  ) any_v
 group by uh, x_group_id
 order by x_nop