events(event_id, user_id, event_type, event_at)

Return unique_likers: how many distinct users produced a 'like' event on 2026-09-15.

The same user liking several times counts once, and other event types on that day count not at all.

Tables

events

event_id  user_id  event_type  event_at
--------  -------  ----------  -------------------
1         10       like        2026-09-15 08:00:00
2         10       like        2026-09-15 19:00:00
3         11       like        2026-09-15 23:59:59
4         12       share       2026-09-15 10:00:00
5         13       like        2026-09-14 23:59:59
6         14       like        2026-09-16 00:00:00

Expected result

unique_likers
-------------
2