How to write a query that will select the amount for each position?

Question

PostgreSQL

Either I'm tired already in the evening, I can't figure it out))
There is a table of users, id, registration_date
It is necessary to take the number of users who registered before it for each date.

Answer 1

Use window functions

select
  distinct(registration_date),
  count(*) over (order by registration_date) as registered
from users
order by registration_date;

Answer 2

select count where ?