update student s, city c
set s.city_name = c.name
where s.city_code = c.code;

update a, b
set a.title=b.title, a.name=b.name
where a.id=b.id

update student s set city_name = (select name from city where code = s.city_code);

UPDATE "SYS_ROLE" A
SET A ."DEPT_ID" = (
  SELECT
    c."id"
  FROM
    "his_department_info" c
  WHERE
    c."dept_name" = A ."ROLE_NAME"