migrate_booking_links.sql

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;