update mail set mail_state = 'terminated' where mail_category in ('无效类', '终止类', '感谢信类'); ALTER TABLE mail ALTER COLUMN contact_id_card DROP NOT NULL; ALTER TABLE mail_source ALTER COLUMN contact_id_card DROP NOT NULL; ALTER TABLE "mailbox"."mail_return" ADD COLUMN "attachments" text; COMMENT ON COLUMN "mailbox"."mail_return"."attachments" IS '附件';