Transact SQL :: Select From A Select Using Row Number With Left Join

The select command below will output one patient’s information in 1 row:

Patient id
Last name
First name
Address 1
OP Coverage Plan 1
OP Policy # 1
OP Coverage Plan 2

[code]...

This works great if there is at least one OP coverage.   There are 3 tables in which to get information which are the patient table, the coverage table, and the coverage history table.   The coverage table links to the patient table via pat_id and it tells me the patient's coverage plan and in which priority to bill.  The coverage history table links to the patient and coverage table via patient id and coverage plan and it gives me the effective date.  

select src.pat_id, lname, fname, addr1,
max(case when rn = 1 then src.coverage_plan_ end) as OP_Coverage1,
max(case when rn = 1 then src.policy_id end) as OP_Policy1,

code]...