To select the nth row without using rwo_number()& order by and cursor :
Here replace top 5 by top 'n'
declare @NewId bigint,@NewFname varchar(20),@NewLname varchar(20),@NewSalary money
select top 5 @NewId =eid,@NewFname = fname @NewLname=lname,@NewSalary=salary from Tbl_Emp_Detail
select @NewId ,@NewFname,@NewLname,@NewSalary
OR
declare @NewId bigint
select top 5 @NewId=eid from Tbl_Emp_Deatail
select * from Tbl_Emp_Detail where eid=@NewId