select first 30 skip 0
    jl.id,
    jl.order_id,
    o.itm_ordernum,
    (select od.date3
     from orders_date_plan od
     where
        UPPER(od.date_description) = 'ЛАКИРОВКА' AND
        od.order_id = o.id
    ) as plan_date,
    (plan_date -jl.lack_date) as delay <= здесь я пытаюсь творить дичь. Или все таки нет и так можно делать?
    ....
from journal_lack jl
    join orders o on o.id = jl.order_id

select first 30 skip 0
    sel.*,
    sel.plan_date -sel.fact_date as delay
from (select
        jl.id,
        jl.order_id,
        o.itm_ordernum,
        (select od.date3
         from orders_date_plan od
         where
            UPPER(od.date_description) = 'ЛАКИРОВКА' AND
            od.order_id = o.id
        ) as plan_date,
        jl.lack_date as fact_date,
        jl.lacknum,
        jl.w_pokras,
        jl.w_pat,
        jl.w_lak,
        jl.comment,    
        jl.freeze_flag
    from journal_lack jl
    join orders o on o.id = jl.order_id ) as sel