Selecting data from two different servers in SQL Server

exec sp_addlinkedserver @server = 'MainServer'

select * from [MainServer].[TestDB].[dbo].[Emp]

Selecting SQL Data with Non-Duplicate Column Values

  select A.ClaimNo
from ClaimsDetails A
join ClaimsDetails B
on A.ClaimNo=B.ClaimNo
where B.IsActive='N'
group by A.ClaimNo
having COUNT(A.ClaimNo) = 1