ALTER TABLE vnr DROP COLUMN rel_old; ALTER TABLE vnr ALTER COLUMN released DROP NOT NULL; ALTER TABLE vnr ALTER COLUMN released SET DEFAULT NULL; UPDATE vnr SET released = NULL WHERE released = '0000-00-00'; ALTER TABLE vn RENAME COLUMN c_years TO c_released; UPDATE vn SET c_released = '0000-00'; ALTER TABLE vn ALTER COLUMN c_released SET DEFAULT '0000-00'; ALTER TABLE vn ALTER COLUMN c_released TYPE character(7); UPDATE vn SET c_released = COALESCE((SELECT SUBSTRING(COALESCE(MIN(released), '0000-00') from 1 for 7) FROM vnr r1 WHERE r1.vid = vn.id AND r1.r_rel = 0 GROUP BY r1.vid ), '0000-00'); ALTER TABLE vn_relations DROP COLUMN lastmod; ALTER TABLE vn ADD COLUMN rgraph bytea NOT NULL DEFAULT '';