php分享（三十六）mysql中关联表更新

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;