SQL query to find if an event is in a list of categories

Question

I have modeled an event to have multiple categories.

So I have an Event table and an Event_Category table. The Event_Category table is obvious: it has two columns, the Event ID and the Category name .

The Categories are HIKE , FAMILY , CLASS_OR_LECTURE , etc.

Maybe I'm having a brain fart but I can't for the life of me figure out the SQL query to get a list of events that are in a given list of Categories.

For example, I want a list of Events that have either of the Categories "HIKE" or "FAMILY".

Can anyone help, please?

Answer 1

select * from events where id in (select distinct id from events_categories where category_id in (1,2))

Answer 2

This isn't it?

SELECT DISTINCT event_id 
  FROM event_category
 WHERE category_name IN ('HIKE', 'FAMILY', 'CLASS_OR_LECTURE')

If you want more than just the event id:

SELECT DISTINCT (whatever) 
  FROM event JOIN event_category USING (event_id)
 WHERE category_name IN ('HIKE', 'FAMILY', 'CLASS_OR_LECTURE')

Answer 3

Select
  e.*
From
  events e
Where
  Exists (
    Select 'x'
    From   event_category ec
    Where  ec.event_id = e.event_id
    And    ec.category_name in ('HIKE', 'FAMILY')
  );