select *
from [Table1] t1
where exists (select 1 from [Table2] t2 where t2.[rf_ServiceID] = t1.[ServiceID] and t2.[Value1] = (select min(t3.[Value1]) from [Table2]))

select * from [Table1] t1
where t1.[ServiceID] in (select top 1 with ties [rf_ServiceID] from [Table2] order by [Value1] ASC)

select *
from [Table1] t1
where exists (select 1 from [Table2] t2 where t2.[rf_ServiceID] = t1.[ServiceID] and t2.[Value1] = (select min(t3.[Value1]) from [Table2] t3))

USE MASTER 
GO

WITH CTE AS
(
  SELECT 507473 AS DOCID,7090 AS SERVICEID
   UNION ALL
  SELECT 507473 AS DOCID,7357 AS SERVICEID
   UNION ALL
  SELECT 507473 AS DOCID,7430 AS SERVICEID
   UNION ALL
  SELECT 507473 AS DOCID, 7430 AS SERVICEID
   UNION ALL
  SELECT 507473 AS DOCID,7430 AS SERVICEID
   UNION ALL
  SELECT 507473 AS DOCID,7430 AS SERVICEID
   UNION ALL
  SELECT 507473 AS DOCID,7476 AS SERVICEID
   UNION ALL
  SELECT 507473 AS DOCID,7476 AS SERVICEID
   UNION ALL
  SELECT 507473 AS DOCID,7476 AS SERVICEID
   UNION ALL
  SELECT 507473 AS DOCID,7289 AS SERVICEID         
),
SERV AS
(
  SELECT 7090 AS SERVICE_ID,1.18 AS VALUE1
   UNION ALL
  SELECT 7289 AS SERVICE_ID,0.5 AS VALUE1
   UNION ALL
  SELECT 7357 AS SERVICE_ID,0.25 AS VALUE1
   UNION ALL
  SELECT 7430 AS SERVICE_ID,0.46 AS VALUE1
   UNION ALL
  SELECT 7432 AS SERVICE_ID,1.25 AS VALUE1
   UNION ALL
  SELECT 7476 AS SERVICE_ID,0.92 AS VALUE1     
)
/*
Вообщем, в таблице 1 в документе с айди 11 serviceid разные, например 100, 155, 138, 120 
и так далее, это ну скажем, выполненные услуги, а их цена во второй таблице, где переменная Value1. 
Мне надо минимальную сумму выбрать из этих выполненных услуг.
*/
SELECT C.DOCID,C.SERVICEID,X.VALUE1
FROM CTE C
CROSS APPLY
(
  SELECT TOP 1 S.SERVICE_ID,S.VALUE1
   FROM SERV S
  ORDER BY S.VALUE1 
)X

Select TOP 1 rf_ServiceID from oms_Tariff order by Value1

select * from Table1 
where ServiceID= 
(Select top 1 rf_ServiceID from Table2 w
here rf_ServiceID in 
(select ServiceID from Table1 where DOCID=507473) order by Value1) and DocID=507473

select * from Table1 
where DocID=507473

select t1.*
  from Table1 t1
 Outer apply (Select top 1 rf_ServiceID 
                from Table2 
               where rf_ServiceID in (select ServiceID from Table1 where DOCID=t1.DOCID) order by Value1) t2
 where ServiceID = rf_ServiceID