How to return multiple fields from subquery - sql

Question

I work in healthcare where we check a patient's insurance to see if their insurance is still active and is eligible for our services. Unfortunately, the database is not very good at associating the eligibility with an appointment or future visit (we have no control over this). As a result, we do not have visibility into what ultimately happens as a result of that eligibility check (did we use that insurance? did the patient not use insurance at all? etc).
What we'd like to do is try to associate the eligibility to a patient's visit that is within a day of that eligibility check (so same day or day before). I'd like to retrieve that visit number and the primary payer for that visit (I'd like the visit number so I can verify that I'm pulling in the correct visit as well as the correct primary payer).
How do I get both pieces of information in the results of my main query? Alternative: how can I spot check the results to verify it is working as desired if I'm only returning the payer name from an inline subquery?
Eligibility Query
select distinct
elig.patient_id,
pm.payer_name,
elig.status,
elig.reject_reason
from
eligibility elig
inner join payer_mstr pm on elig.payer_id=pm.payer_id
where
elig.create_timestamp>='2019-01-01' and elig.create_timestamp<'2019-02-01'
Associated Encounter and Payer Data and Tables
select distinct
pe.enc_nbr,
pm.payer_name
from
patient_encounter pe --visit data
--encounter_payer holds payer data for a specific visit, and 1 means primary payer
left join encounter_payer epay on pe.enc_id=epay.enc_id and cob=1
left join payer_mstr pm on epay.payer_id=pm.payer_id
I'm on Microsoft SQL Server 2008 R2

Answer 1

You could try using a common table expression. Works like a subquery and you can add all the fields you would like to have from it.
Common Table Expressions
WITH cte AS (
select
pe.enc_nbr,
pm.payer_name,
pm.payer_id,
ROW_NUMBER() OVER(PARTITION BY pm.payer_id ORDER BY pm.payer_id ASC) AS row_num --If you have a date created on each row I would change the pm.payer_id field that and change it to ORDER BY <field> DESC
from
patient_encounter pe --visit data
--encounter_payer holds payer data for a specific visit, and 1 means primary payer
left join encounter_payer epay on pe.enc_id=epay.enc_id and cob=1
left join payer_mstr pm on epay.payer_id=pm.payer_id
--Here you could add a WHERE clause to narrow your search date down to get previous or current date if you have a date field just use WHERE date >= DATEADD(d,-1,GETDATE())
)
select distinct
elig.patient_id,
pm.payer_name,
elig.status,
elig.reject_reason,
cte.enc_nbr
from
eligibility elig
inner join payer_mstr pm on elig.payer_id=pm.payer_id
left join cte ON cte.pm.payer_id = pm.payer_id --Now you can pull in any fields you need and can see if they have a record or do not
where
elig.create_timestamp>='2019-01-01' and elig.create_timestamp<'2019-02-01'

Answer 2

Hard to test your very specific question, but try this:
SELECT DISTINCT
elig.patient_id,
pm.payer_name,
elig.status,
elig.reject_reason
pe.enc_nbr
FROM
patient_encounter pe
LEFT JOIN encounter_payer epay on pe.enc_id=epay.enc_id and cob=1
LEFT JOIN payer_mstr pm on epay.payer_id=pm.payer_id
LEFT JOIN eligibility elig on elig.payer_id=pm.payer_id
WHERE
elig.create_timestamp>='2019-01-01' and elig.create_timestamp<'2019-02-01'