PostgreSQL - Using a Subquery to Update Multiple Column Values

Question

I need to be able to update multiple columns on a table using the result of a subquery. A simple example will look like below -

UPDATE table1
SET (col1, col2) =         


        

Answer 1

Using UPDATE FROM is a good solution when you don't have simple subselects. In this UPDATE I wanted to set the event_profile_id of the photos table to be the owner (event profiles are owners too) of the photo set the photo belongs to.

UPDATE photos
SET event_profile_id=photos_and_events.event_profile_id
FROM (
  SELECT
    ph.id photo_id,
    pr.id event_profile_id
  FROM photos ph, profiles pr, photo_sets ps
  WHERE ph.main_photo_set_id=ps.id AND ps.owner_profile_id=pr.id
) AS photos_and_events
WHERE photos.id=photos_and_events.photo_id;