在Postgresql中我需要重构一个表(Purchases);它有另一个表(Shop)的外键.相反,我想要两个以文本方式保持关系的字段.我不能丢失任何信息,表格已包含数据.
Purchases.shop_id: (long) -- is the field I need to drop Purchases.shop: (characters) -- will hold the Shop's name Purchases.shop_user: (characters) -- will hold the Shop's user name. Shop.id: (long,pk) -- still referenced from Purchases Shop.name: (characters) -- Shop's name Shop.user: (characters) -- Shop's user name
两个字段是必需的,因为Shop在(名称,用户)上是唯一的(或者当然是id).
ALTER TABLE Purchases ADD COLUMN shop CHARACTER VARYING(255); ALTER TABLE Purchases ADD COLUMN shop_user CHARACTER VARYING(255); -- ??? ALTER TABLE Purchases DROP CONSTRAINT shop_id_fk; ALTER TABLE Purchases DROP COLUMN shop_id;
所以开始和结束很容易,有人可以帮助中间部分吗？ 原文链接：https://www.f2er.com/mssql/79966.html
