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一：关联不同的表更新
1: 通过where关联更新
update student s, city c set s.province_name = c.province_name, s.city_name = c.name where s.city_code = c.code;
2：子查询更新
update student s set city_name = (select name from city where code = s.city_code);
子查询更新优化：
UPDATE t_advs_order SET attribute1=(SELECT o.order_state FROM tk_zyt_scenery_order o WHERE o.order_id=`on`), attribute2=(SELECT o.order_state FROM tk_zyt_scenery_order o WHERE o.order_id=`on`) WHERE EXISTS (SELECT o.order_state FROM tk_zyt_scenery_order o WHERE o.order_id=`on`);
转为：
UPDATE t_advs_order a
INNER JOIN tk_zyt_scenery_order s ON s.order_id=a.`on`
SET
a.attribute1=s.order_id,
a.attribute2=s.order_id;
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原文地址：http://www.cnblogs.com/Alight/p/5416900.html
