《Mysql應用MySQL 從一張表update字段到另外一張表中》要點：
本文介紹了Mysql應用MySQL 從一張表update字段到另外一張表中，希望對您有用。如果有疑問，可以聯系我們。
先來幾個簡單的示例MYSQL應用
Solution 1:? 1列MYSQL應用
update student s, city c set s.city_name = c.name where s.city_code = c.code;
Solution 2:? 多個列MYSQL應用
update a, b set a.title=b.title, a.name=b.name where a.id=b.id
Solution 3: 子查詢MYSQL應用
update student s set city_name = (select name from city where code = s.city_code);
我們再來看幾個負責寫的MYSQL應用
例如: 把表 tk_zyt_scenery_order的 字段更新到 t_advs_order中去, 一般可能會這樣寫:
MYSQL應用
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`);
這樣效率比較低下, 優化寫法:
MYSQL應用
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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