SELECT (MOZ_RAO-SL_RAO) as kss,*from (SELECT barcode,      SUM(CAST(items as decimal (18,4)))as SL_RAO
  FROM [ITN_SOFT].[dbo].[SALES]
  
  where clientid!='111111111'   group by barcode ) as t1
  
  left join (SELECT barcode as MOZ_bar,  SUM(CAST(raodenoba as decimal (18,4)))as MOZ_RAO
  FROM [ITN_SOFT].[dbo].[MOZRAOBA]  group by barcode )as t2
  on t1.barcode=t2.MOZ_bar
  
  order by kss