with base as (
select
employee_id,
to_dt,
from_dt,
lag(to_dt) over (partition by employee_id order by from_dt) lag_to_dt
from abakhytbekuly.salary
),
error as (
select 
employee_id,
from_dt,
case when
     lag_to_dt > from_dt then 'пересечение'
     when 
     lag_to_dt < from_dt then 'дыра'
     end as status
from base
where lag_to_dt is not null  
)
select *
from error
order by employee_id, from_dt