full_booking_link_migration.sql

-- upgrade

WITH reserv_data AS (
    SELECT nextval('roombooking.reservation_links_id_seq') AS new_link_id, id AS reserv_id, event_id
    FROM roombooking.reservations
    WHERE event_id IS NOT NULL
    -- LIMIT 2
), link_ids_data AS (
    INSERT INTO roombooking.reservation_links (id, event_id, linked_event_id, link_type)
    SELECT new_link_id, event_id, event_id, 2 -- LinkType.event
    FROM reserv_data
    RETURNING id AS link_id
)
UPDATE roombooking.reservations
SET link_id = link_ids_data.link_id
FROM link_ids_data,reserv_data
WHERE id = reserv_data.reserv_id and link_ids_data.link_id = reserv_data.new_link_id;
-- op.drop_column('reservations', 'event_id', schema='roombooking')
 
 -- downgrade
 
ALTER TABLE roombooking.reservations
ADD COLUMN event_id_test INT;
 
UPDATE roombooking.reservations
SET event_id_test = reserv_link.event_id
FROM (
    SELECT id, event_id
    FROM roombooking.reservation_links
    WHERE event_id IS NOT NULL
) reserv_link
WHERE link_id = reserv_link.id;