Question

I need to make a query which displays an organizations order descreasing in order by the organizations’ rank.
However, if organizations have an event that is currently happening, they are displayed at the top (ordered by rank)
Then organizations with upcoming events are displayed
And lastly organizations with nothing happening are displayed.

An organization can have both currently happening and upcoming events, and have multiples of each, but it only chooses one event and the organization only appears under on category

Currently happening is a priority over upcoming, so the organization only appears in currently happening if it has both currently happening and upcoming events

Here is an example of what the output should be

Currently Happening

• Organization 1 (Rank 3) – Event1
• Organization 2 (Rank 2) – Event2
• Organization 3 (Rank 1) – Event3

Upcoming

• Organization 5 (Rank 3) – Event4
• Organization 4 (Rank 2) – Event5
• Organization 6 (Rank 2) – Event6

Nothing

• Organization 7 (Rank 3) – Event7
• Organization 8 (Rank 2) – Event8
• Organization 9 (Rank 2) – Event9

Here is an example table set-up

Organizations
id – name – rank

Events
id – organization_id – name – status (2 = currently happening, 1 = upcoming, 0 = nothing)

The status column just contains either 2, 1, or 0 as I said which I believes makes it possible to do an ORDER BY

If someone could write an example query I would greatly appreciate it! I’m having trouble with ordering the events by the status and then ordering the organizations of those events by their rank at the same time.

Answer 1

Example:

SELECT o.*, max(e.status) AS org_status
FROM   organization o
JOIN   event e ON e.organiszation_id = o.organization_id
GROUP  BY o.organization_id
ORDER  BY org_status DESC, o.rank DESC, o.name;

Note that I use organization_id as primary key of organization as it is an anti-pattern to use the non-descriptive name id in multiple tables across the database.

The fact that o.organization_id is the primary key also allows me to only GROUP BY o.organization_id – this works since PostgreSQL 9.1.