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UPDATE���ޥ�ɤ���Ѥ��ơ���¸�ιԤ򹹿����뤳�Ȥ��Ǥ��ޤ��� 11��28���ʹߤ����Ƥε������ɤ߼�꤬2�ٹ⤯�ʤäƤ��뤳�Ȥ��狼�ä��Ȥ��ޤ��� ���ξ�硢�ʲ��Υ��ޥ�ɤˤ�äơ��ǡ����򹹿����뤳�Ȥ��Ǥ��ޤ���

UPDATE weather
    SET temp_hi = temp_hi - 2,  temp_lo = temp_lo - 2
    WHERE date > '1994-11-28';

�ǡ����ι�����ξ��֤��ǧ���ޤ���

SELECT * FROM weather;

     city      | temp_lo | temp_hi | prcp |    date
---------------+---------+---------+------+------------
 San Francisco |      46 |      50 | 0.25 | 1994-11-27
 San Francisco |      41 |      55 |    0 | 1994-11-29
 Hayward       |      35 |      52 |      | 1994-11-29
(3 rows)