问题
On my mysql DB with inno_db engine,
I have a table with a foreign key. I want to drop the column (along with the foreign key and the associated index of course - i don't need the whole column!)
Now, simply dropping it yields an error: General error: 1025 Error on rename of '.\road_dmy#sql-19d8_2be' to '.\road_dmy\contact' (errno: 150)
It sounds like this is a known issue. http://bugs.mysql.com/bug.php?id=15317
But anyway, what should i do to drop this column? I'm very sure it's possible nobody would use this DB otherwise
(and b.t.w. how can I know the true details of the mysterious error message above?)
回答1:
You must drop the key first. I don't know the names of your tables but I'll give you the general strategy by example. Suppose you have the following 2 InnoDB tables:
CREATE TABLE `A` (
`id` int(10) unsigned NOT NULL auto_increment,
PRIMARY KEY (`id`)
) ENGINE=InnoDB;
CREATE TABLE `B` (
`id` int(10) unsigned NOT NULL auto_increment,
`a_id` int(10) unsigned NOT NULL,
PRIMARY KEY (`id`),
KEY `a_id` (`a_id`),
CONSTRAINT `b_ibfk_1` FOREIGN KEY (`a_id`) REFERENCES `a` (`id`)
) ENGINE=InnoDB;
You can drop the a_id
column in table B
using the following command:
alter table B drop foreign key b_ibfk_1, drop column a_id;
来源:https://stackoverflow.com/questions/5589355/dropping-a-column-with-a-foreign-key