SQL count DISTINCT ONCE user_id multiple attributes - sql

Question

Hello there I cant manage to get a good result for the following case:
I have a table which is like this:
UserID | Label
-------- ------
1 | Private
1 | Public
2 | Private
3 | Hidden
4 | Public
5 | Hidden
I want to have the following happening if a User has following assigned he is:
Private and Hidden are treaten the same: lets say Business
Public: BtoC
Public and Private and/or Hidden: both
So in the end I have a count(DISTINCT UserID) of
Business 3
BtoC 1
both 1
I have tried to use CASE WHEN but it doesn't work my current total query looks like this:
SELECT gen_month,
count(DISTINCT cu.id) as leads,
a.label
FROM generate_series(DATE_TRUNC('month', CURRENT_DATE::date - 96*INTERVAL '1 month'), CURRENT_DATE::date, '1 month') m(gen_month)
LEFT OUTER JOIN company_user AS cu
ON (date_trunc('month', cu.creation_date) = date_trunc('month', gen_month))
LEFT JOIN user u
ON u.user_id = cu.id
LEFT join user_account_status as uas
on cu.id = uas.user_id
LEFT JOIN account as a
on uas.account_id = a.id
where gen_month >= DATE_TRUNC('month',NOW() - INTERVAL '5 months')
group by m.gen_month, a.label
order by gen_month
So my main problem now is that the count appears in every attribute once.
How can I make a userid only count once under condition CASE WHEN user_id appears Public and (Private or Hidden) THEN count(DISTINCT user_id) as Both?
Addition: its mySQL mariaDB and postgreSQL. But first I would happy with Postgres

Answer 1

This is not implemented in your total query, but for counting users for each category, you can:
with the_table(UserID , Label) as(
select 1 ,'Private' union all
select 1 ,'Public' union all
select 2 ,'Private' union all
select 3 ,'Hidden' union all
select 4 ,'Public' union all
select 5 ,'Hidden'
)
select result, count(*) from (
select UserID, case when min(Label) = 'Public' then 'BtoC' when max(Label) in('Private','Hidden') then 'Business' else 'both' end as result
from the_table
group by UserID
) t
group by result

Answer 2

with
my_table(user_id, label) as (values
(1,'Private'),
(1,'Public'),
(2,'Private'),
(3,'Hidden'),
(4,'Public'),
(5,'Hidden')),
t as (
select
user_id,
string_agg('{'||label||'}', '') as labels
from my_table
group by user_id),
tt as (
select
user_id,
labels,
case
when
position('{Public}' in labels) > 0 and (position('{Private}' in labels) > 0 or position('{Hidden}' in labels) > 0) then 'Both'
when
position('{Private}' in labels) > 0 or position('{Hidden}' in labels) > 0 then 'Business'
when
position('{Public}' in labels) > 0 then 'BtoC'
end as kind
from t)
select kind, count(*) from tt group by kind;
For MariaDB use GROUP_CONCAT() instead of PostgreSQL string_agg().
Note that the case statement check conditions in order of appearance and returns the value for the first satisfied condition.
PS: Using PostgreSQL's arrays the conditions would be more elegant.