Summing Custom Column - mysql

Question

First Stackoverflow question - so go easy on me :).
Hello, I am trying to flag items as "Attributed" using the following query that I have written. Essentially, if a patient ID has a PERSON_PROVIDER_RELATIONSHIP flag, they are given a 1 for that instance. If they have another type of flag (there are two other possible flags you can receive). Everything goes fine (the assigning of "1" to the instances of PERSON_PROVIDER_RELATIONSHIP), but then when I try to sum that custom column I created ("Attribution"), I get this error: (Column "Attribution" does not exist). I get this error whether I try to make another column that does the summing or when I add a "having" clause to the end where I state I only want to see records with a sum of >0. Any help would be appreciated here! I'm using MySQL to write this and am happy to provide any clarifying information.
select distinct c.empi_id as "Patient",
c.incurred_from_date as "Service Date",
(case when c.billing_organization_source_id IN ('xxxx','yyyy') then 1 else 0
end) as "In-Network Indicator",
(case when t.ref_record_type = 'PERSON_PROVIDER_RELATIONSHIP' then 1 else 0
end) as "Attribution",
(sum("Attribution") over (partition by c.empi_id)) as "Attribution Flag",
p.cleanprovidername as "Provider", t.ref_record_type
from ph_f_annotated_claim c
left outer join PH_F_Attribution_Component_Data_Point t
on t.empi_id = c.empi_id and t.population_id = c.population_id
inner join ph_d_personnel_alias a
on a.prsnl_id = t.prsnl_id
inner join xxxx_xxxx_xxxx_xxxx p
on a.prsnl_alias_id = p.NPI
where (c.bill_type_code like '33%'
or c.bill_type_code like '32%'
or c.bill_type_code like '033%'
or c.bill_type_code like '032%')
and c.source_description = 'MSSP Claims'
and c.incurred_from_date >= '2015-12-01'
and c.incurred_from_date <= '2017-01-31'
and c.population_id = '2feb2cb1-be55-4827-a21f-4e2ef1a40340'
and p.DegreeName IN ('MD','DO')
and a.prsnl_alias_type = 'NPI'
and p.PrimaryPHO = 'Yes'
group by c.empi_id, c.incurred_from_date, c.billing_organization_source_id,
p.cleanprovidername, t.ref_record_type

Answer 1

You can't use an aliased column name as an expression in the same SELECT clause. You have to do something like this:
sum(case when t.ref_record_type = 'PERSON_PROVIDER_RELATIONSHIP' then 1 else 0 end) over (partition by c.empi_id) as "Attribution Flag"