select
contragent_descr = contragents.descr,
contragent_type = contragent_types.descr,
contragent_type_short = contragent_types.descr_short
from contragents
inner join contragent_types on contragent_types.contragent_type_id=contragents.contragent_type_id
select top 1 from (
select .. from детальные_данные where ..
union all
select .. from страны where ..
union all
select .. from континенты where ..
)