问题描述
我在 mysql 中试过这个:
I tried this in mysql:
mysql> alter table region drop column country_id;
得到这个:
ERROR 1025 (HY000): Error on rename of './product/#sql-14ae_81' to
'./product/region' (errno: 150)
有什么想法吗?外键的东西?
Any ideas? Foreign key stuff?
推荐答案
如果您的表使用 InnoDB 引擎，您通常会收到此错误.在这种情况下，您必须删除外键，然后执行更改表并删除列.
You usually get this error if your tables use the InnoDB engine. In that case you would have to drop the foreign key, and then do the alter table and drop the column.
但棘手的部分是您不能使用列名删除外键，而是必须找到用于索引它的名称.要找到它，请发出以下选择:
But the tricky part is that you can't drop the foreign key using the column name, but instead you would have to find the name used to index it. To find that, issue the following select:
显示创建表区域；
这应该会显示索引的名称，如下所示:
This should show you the name of the index, something like this:
CONSTRAINT region_ibfk_1 FOREIGN关键 (country_id) 参考country (id) ON DELETE NO更新操作无操作
CONSTRAINT
region_ibfk_1FOREIGN KEY (country_id) REFERENCEScountry(id) ON DELETE NO ACTION ON UPDATE NO ACTION
现在只需发出一个:
alter table region 删除外键region_ibfk_1;
alter table region drop foreign key
region_ibfk_1;
最后是:
更改表区域删除列country_id;
alter table region drop column country_id;
你可以走了！
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