Select distinct on value must appear in group by - postgresql

Question

I am encountering an error when trying to run the below query: "column "v.visit_id" must appear in the GROUP BY clause or be used in an aggregate function."
My question is that I believe that I am already using this column in an aggregate function on line 2 count(v.visit_id) as total_visits. Does this not count as satisfying the error? I can't add to the GROUP BY directly since that would mess up my output.
My end goal is to select distinct visit IDs while also only grouping the output by physician names.
select distinct on (v.visit_id)
count(v.visit_id) as total_visits,
sum(mad2.nsma1_ans::time - mad.nsma1_ans::time) as or_hours_utilized,
sum(esla1_bt_end[1] - esla1_bt_beg[1]) as total_block_hours,
sum(extract(epoch from mad2.nsma1_ans::time) - extract(epoch from mad.nsma1_ans::time)) /
(sum(extract(epoch from esla1_bt_end[1])) - sum(extract(epoch from esla1_bt_beg[1]))) * 100 as or_percentage,
pt1.phys1_name as surgeon
from visit as v
inner join pat_phy_relation_table as pprt
on pprt.patphys_pat_num = v.visit_id
and pprt.patphys_rel_type = 'ATTENDING'
inner join physician_table1 as pt1
on pt1.phys1_num = pprt.patphys_phy_num
and pt1.phys1_arid = v.visit_arid --need to confirm how to handle ARIDs
inner join ews_location_table2 elt2
on lpad(pt1.phys1_num::varchar, 6, '0') = any (elt2.esla1_bt_surg)
and esla1_loca in ('OR1','OR2','OR3','OR4')
and esla1_date between '2021-09-01' and '2021-09-30'
and esla1_seid = pt1.phys1_arid
inner join multi_app_documentation mad2
on mad2.nsma1_patnum = v.visit_id
and mad2.nsma1_code = 'OROUT' --only pulling visits/physicians with an OROUT
and mad2.nsma1_ans !~ '[x,X,C,END,S]' --removing non-standard data
and mad2.nsma1_ans != '' and mad2.nsma1_ans != '0' and mad2.nsma1_ans != '1' and mad2.nsma1_ans != '0000'
inner join multi_app_documentation mad
on mad.nsma1_patnum = v.visit_id
and mad.nsma1_code = 'ORINTIME' --only pulling visits/physicians with an ORINTIME
where v.visit_admit_date between '2021-09-01' and '2021-09-30'
and v.visit_arid = 5
group by pt1.phys1_name

Answer 1

The problem is distinct on (v.visit_id) is not an aggregate function. You'd need to add it to the group by.
select
distinct on (v.visit_id)
count(v.visit_id) as total_visits,
...
group by v.visit_id, pt1.phys1_name
However, it makes no sense to use distinct on something you're grouping by. The group by will already only show one row for each visit_id.
select
v.visit_id,
count(v.visit_id) as total_visits,
...
group by v.visit_id, pt1.phys1_name
If v.visit_id is a primary key or unique this also makes no sense. Each visit_id will only appear once and your count will always be 1. You probably want to leave it out entirely.
select
count(v.visit_id) as total_visits
...
group by pt1.phys1_name