MySQL 从一张表update字段到另外一张表中

先来几个简单的示例

Solution 1:  1列

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123	update student s, city c  set s.city_name = c.name where s.city_code = c.code;

Solution 2:  多个列

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1234	update a, b  set a.title=b.title, a.name=b.namewhere a.id=b.id

Solution 3: 子查询

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1	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

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:

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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:

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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;