Select
...
sum(case when (nat_vq.vag_num mod  10000000 ) =  5  then  1  else  0  end) as park,
...

Select
...
sum(case when (nat_vq.vag_num)  like '5%' then  1  else  0  end) as park,
...

case when SubStr(nat_vq.vag_num, 0 , 1 ) = '5' then  1  else  0  end

sum(nat_vq.netto)/Count(nat_vq.vag_num)

select
       tu3nat.mm_d,
       tu3nat.mm_dor,
       tu3nat.mm_id,
       mmlst_vags.poezd_num,
       tu3nat.nat_id,
       nat_vq.vag_num,
       case when SubStr(cast(nat_vq.vag_num as char( 8 )), 1 , 1 ) = '5' then  1  else  0  end as park,
       sum(nat_vq.netto)/Count(nat_vq.vag_num) as sr_proiz 
from
 (
  select 
         mmlst.mm_d,
         mmlst.mm_dor,
         mmlst.mm_id,
         mmlst.rec_num,
         mmlst.dep_dt,
         max(nat.nat_id) as nat_id
  from mmdoc.mmmslog mmslog
  left join mmdoc.mmmslog mmslogd on
                                     mmslogd.dd_mm_d=mmslog.mm_d
    inner join mmdoc.mmmlst mmlst on
                                   mmlst.mm_id=mmslog.mm_id
   where
         mmlst.prg='1000'
  group by 
           mmlst.mm_d,
           mmlst.mm_dor,
           mmlst.mm_id,
           mmlst.rec_num,
           mmlst.dep_dt
 ) as tu3nat
inner join asoup.poezd_nat_vq nat_vq on
                                        nat_vq.nat_id=tu3nat.nat_id
inner join
 (
  select 
             vags.mm_d,
             vags.mm_dor,
             vags.mm_id,
             vags.poezd_num,
             min(vags.rec_num) as rec_num,
             coalesce(vags.rec_num_next, 300 ) as rec_num_next
  from
   (

    select 
               mmlst1.mm_d,
               mmlst1.mm_dor,
               mmlst1.mm_id,
               mmlst1.poezd_num,
               mmlst1.rec_num,
               min(mmlst2.rec_num) as rec_num_next
    from mmdoc.mmmlst mmlst1
    left join mmdoc.mmmlst mmlst2 on
                 mmlst1.mm_d=mmlst2.mm_d and
                 (
                   mmlst2.wnet is null or mmlst1.wnet<>mmlst2.wnet or
                   mmlst2.wbr is null or mmlst1.wbr<>mmlst2.wbr
                 )
    where
          mmlst1.pr_vq='20'  
    group by
             mmlst1.mm_d,
             mmlst1.mm_dor,
             mmlst1.mm_id,
             mmlst1.poezd_num,		
             mmlst1.rec_num
   ) vags
  group by 
           vags.mm_d,
           vags.mm_dor,
           vags.mm_id,
           vags.poezd_num,
           vags.rec_num_next
 ) mmlst_vags 

on
                 mmlst_vags.mm_d=tu3nat.mm_d
group by
	tu3nat.mm_d,
	tu3nat.mm_dor,
	tu3nat.mm_id,
	mmlst_vags.poezd_num,
	tu3nat.rec_num,
 	tu3nat.nat_id,
	nat_vq.vag_num,
	case when SubStr(cast(nat_vq.vag_num as char( 8 )), 1 , 1 ) = '5' then  1  else  0  end--,
	sum(nat_vq.netto)/Count(nat_vq.vag_num);