《Mysql应用MySQL 从一张表update字段到另外一张表中》要点：
本文介绍了Mysql应用MySQL 从一张表update字段到另外一张表中，希望对您有用。如果有疑问，可以联系我们。
先来几个简单的示例MYSQL应用
Solution 1: 1列MYSQL应用
update student s, city c set s.city_name = c.name where s.city_code = c.code;
Solution 2: 多个列MYSQL应用
update a, b set a.title=b.title, a.name=b.name where a.id=b.id
Solution 3: 子查询MYSQL应用
update student s set city_name = (select name from city where code = s.city_code);
我们再来看几个负责写的MYSQL应用
例如: 把表 tk_zyt_scenery_order的 字段更新到 t_advs_order中去, 一般可能会这样写:
MYSQL应用
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`);
这样效率比较低下, 优化写法:
MYSQL应用
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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