text: UPDATE staff SET salary=salary*1.1 WHERE name='SMITH';
  ----
  UPDATE staff AS U SET U.salary=U.salary/1.95583, U.currency='EUR'
  WHERE U.currency='DM';
  ----
  UPDATE staff AS U
  SET U.salary=V.salary, U.currency=V.currency
  FROM staff AS U, staff_updates AS V
  WHERE U.name=V.name;
  ----
  UPDATE order_pos
  SET stocks=stocks*10
  PREFERRING HIGH (order_date) PARTITION BY (shop_id, order_id);
  ----
  UPDATE
  	t1
  SET
  	x=t2.c1,
  	w=t4.c2
  FROM
  	t2
  	JOIN t3 g ON t2.c1=t3.c2
  	LEFT JOIN t4 ON t4.c3=t3.c1
  ;
  