I am trying to drop a FOREIGN KEY but it is throwing an error.
**mysql> alter table traveltime drop foreign key travelid;
ERROR 1091 (42000): Can't DROP 'travelid'; check that column/key exists
mysql>**
The column travelid is the foreign key referencing to another table. Here is the output of SHOW CREATE TABLE traveltime;
CREATE TABLE `traveltime` (
`timeid` int(11) DEFAULT NULL,
`travelid` int(11) DEFAULT NULL,
`hour` int(11) DEFAULT NULL,
`minute` int(11) DEFAULT NULL,
KEY `travelid` (`travelid`),
CONSTRAINT `traveltime_ibfk_1` FOREIGN KEY (`travelid`) REFERENCES `travel` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
The column on which the FOREIGN KEY was defined was travelid, but you probably did not specify an identifier for the constraint itself when it was created, and MySQL created one on your behalf: traveltime_ibfk_1.. That's the identifier you need to target in your ALTER statement.
ALTER TABLE traveltime DROP FOREIGN KEY traveltime_ibfk_1
Though it's difficult to visually parse, MySQL's ALTER TABLE docs specify
ALTER [IGNORE] TABLE tbl_name
[alter_specification [, alter_specification] ...]
[partition_options]
alter_specification:
table_options
...
...
DROP FOREIGN KEY fk_symbol
... where fk_symbol is the constraint's identifier name, rather than the column on which it was defined (because it is possible to define multi-column FK's).
Related
I have a table in MySQL like this (this is returned from using show create table user_org_contacts):
CREATE TABLE `user_org_contacts` (
`user_org_contacts_id` int(11) NOT NULL AUTO_INCREMENT,
`from_user_id` int(11) DEFAULT NULL,
`to_org_user_id` int(11) DEFAULT NULL,
`suggested_vacancy_id` int(11) DEFAULT NULL,
`contact_date` datetime NOT NULL,
`message` text,
PRIMARY KEY (`user_org_contacts_id`),
KEY `FK_Reference_53` (`from_user_id`),
KEY `FK_Reference_54` (`to_org_user_id`),
KEY `FK_Reference_55` (`suggested_vacancy_id`)
) ENGINE=InnoDB AUTO_INCREMENT=18 DEFAULT CHARSET=latin1
I have noticed that my FK_Reference_54 is wrong and points to the wrong table. So I would like to change this one by the correct FK.
This is what I tried:
ALTER TABLE `user_org_contacts`
DROP FOREIGN KEY `FK_Reference_54`;
ALTER TABLE `user_org_contacts`
ADD CONSTRAINT `FK_Reference_54`
FOREIGN KEY (`to_org_user_id`) REFERENCES `users` (`user_id`) ON DELETE CASCADE;
This produces the following error:
1091 - Can't DROP 'FK_Reference_54'; check that column/key exists
The problem is that you are confusing indexes with primary keys.
The keyword KEY is actually showing you indexes while primary keys use the keywords CONSTRAINT ... FOREIGN KEY ...
Example:
CONSTRAINT `FK_name` FOREIGN KEY (`current_field_name`)
REFERENCES `external_table_name` (`external_field_name`) ON DELETE CASCADE ON UPDATE CASCADE
So in your case, if you want to remove your INDEX you just need to call this query
ALTER TABLE `user_org_contacts`
DROP INDEX `FK_Reference_54`;
Next time I suggest you using some UI for mysql like mysql workbench, with that you would have noticed the issue immediatly.
First Try To remove that column
ALTER TABLE tablename DROP COLUMN columname;
Then:
ALTER TABLE tablename ADD columnname datatype.
Or you can try this Modify option like.
ALTER TABLE tablename MODIFY COLUMN columnname datatype;
Hope This will help you.
I have the following 2 tables:
CREATE TABLE `personal_info` (
`p_id` int(11) NOT NULL AUTO_INCREMENT,
`name` text NOT NULL,
`initials` text NOT NULL,
`surname` text NOT NULL,
`home_lang` int(11) NOT NULL,
PRIMARY KEY (`p_id`),
KEY `home_lang` (`home_lang`),
CONSTRAINT `personal_info_ibfk_1` FOREIGN KEY (`home_lang`) REFERENCES `language_list` (`ll_id`)
) ENGINE=InnoDB AUTO_INCREMENT=44 DEFAULT CHARSET=latin1
CREATE TABLE `language_list` (
`ll_id` int(11) NOT NULL AUTO_INCREMENT,
`name` text NOT NULL,
PRIMARY KEY (`ll_id`)
) ENGINE=InnoDB AUTO_INCREMENT=73 DEFAULT CHARSET=latin1
I am trying to remove a column from a table with the following:
ALTER TABLE `personal_info` DROP `home_lang`
But cannot do it since I recieve this error:
#1025 - Error on rename of '.\MyDB\#sql-112c_82' to '.\MyDB\personal_info' (errno: 150)
I have tried to first remove the index and then remove the column with this:
ALTER TABLE personal_info DROP INDEX home_lang
But then I get the following error:
#1553 - Cannot drop index 'home_lang': needed in a foreign key constraint
So I tried to drop the foreign key:
ALTER TABLE personal_info DROP FOREIGN KEY home_lang
But received this error:
#1025 - Error on rename of '.\MyDB\personal_info' to '.\MyDB\#sql2-112c-8d' (errno: 152)
I have also tried to first set all the values to null:
update personal_info set home_lang = null
But then received this error:
#1452 - Cannot add or update a child row: a foreign key constraint fails (`MyDB`.`personal_info`, CONSTRAINT `personal_info_ibfk_1` FOREIGN KEY (`home_lang`) REFERENCES `language_list` (`ll_id`))
And now I am stuck. I have tried a few things but just cannot get the column removed. I am not allowed to alter the DB in any way other than removing the column.
Your DROP FOREIGN KEY syntax is using the wrong key name. It's trying to drop your "plain" index on the home_lang field. It's NOT the foreign key itself.
CONSTRAINT `personal_info_ibfk_1` FOREIGN KEY (`home_lang`) REFERENCES `language_list` (`ll_id`)
^^^^^^^^^^^^^^^^^^^^^--- THIS is the name of the foreign key
Try:
ALTER TABLE personal_info DROP FOREIGN KEY `personal_info_ibfk_1`
Use this given below query to find the name of the foreign key.
SHOW CREATE TABLE forms_main;
Then once u got the key, execute drop foreign key command
alter TABLE `forms_main`
drop FOREIGN key `forms_main_ibfk_1`;
Then execute the drop column command
ALTER TABLE `forms_main` DROP `company_id`;
ALTER TABLE db_name.table_name
DROP FOREIGN KEY foreign_key;
ALTER TABLE test.exam
DROP INDEX id ;
Table CARGO
DROP TABLE IF EXISTS "hibernatecurso"."cargo";
CREATE TABLE "hibernatecurso"."cargo" (
"idcargo" int(11) NOT NULL DEFAULT '0',
"funcao" varchar(45) DEFAULT NULL,
PRIMARY KEY ("idcargo")
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
Table EMPREGADO
DROP TABLE IF EXISTS "hibernatecurso"."empregado";
CREATE TABLE "hibernatecurso"."empregado" (
"idempregado" int(11) NOT NULL DEFAULT '0',
"nome" varchar(45) NOT NULL DEFAULT '',
"cargo" varchar(45) NOT NULL DEFAULT '',
PRIMARY KEY ("idempregado"),
KEY "idx_cargo" ("cargo")
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
create index in empregado
ALTER TABLE `hibernatecurso`.`empregado` ADD INDEX `idx_cargo`(`cargo`);
Create FK in empregado
ALTER TABLE `hibernatecurso`.`empregado` DROP INDEX `idx_cargo`,
ADD INDEX `idx_cargo`(`cargo`),
ADD CONSTRAINT `FK_empregado_cargo` FOREIGN KEY `FK_empregado_cargo` (`cargo`)
REFERENCES `cargo` (`funcao`)
ON DELETE CASCADE
ON UPDATE CASCADE;
in this part....
Error while executing query.
ALTER TABLE `hibernatecurso`.`empregado` DROP INDEX `idx_cargo`,
ADD INDEX `idx_cargo`(`cargo`),
ADD CONSTRAINT `FK_empregado_cargo` FOREIGN KEY `FK_empregado_cargo` (`cargo`)
REFERENCES `cargo` (`funcao`)
ON DELETE CASCADE
ON UPDATE CASCADE;
MySQL Error Number 1215
Cannot add foreign key constraint
What is causing the error?
I maybe have hard time reading, but I don't see any index on cargo.funcao. This is very probably missing:
ALTER TABLE `hibernatecurso`.`cargo` ADD INDEX `idx_funcao`(`funcao`);
InnoDB permits a foreign key to reference any index column or group of columns.
However, in the referenced table, there must be an
index where the referenced columns are listed as the first columns in
the same order.
http://dev.mysql.com/doc/refman/5.1/en/innodb-foreign-key-constraints.html
I had the same kind of issue and I fixed it by making sure that collation and types matched in both FK and the parent PK.
I am trying to drop a number of foreign keys using:
ALTER TABLE `table` DROP FOREIGN KEY `fk_table_users1` , DROP FOREIGN KEY `fk_table_accounts1` , DROP FOREIGN KEY `fk_table_data1` ;
but it returns the error:
Error on rename of './db/table' to './db/#sql2-179c-288289' (errno: 152)
I have run SHOW ENGINE INNODB STATUS which says:
120725 12:38:37 Error in dropping of a foreign key constraint of table db/table,
in SQL command
ALTER TABLE `table` DROP FOREIGN KEY `fk_table_users1` , DROP FOREIGN KEY `fk_table_accounts1` , DROP FOREIGN KEY `fk_table_data1`
Cannot find a constraint with the given id fk_table_users1.
SHOW CREATE TABLE 'table' output:
CREATE TABLE `table` (
`id` int(11) NOT NULL auto_increment,
`data_id` int(11) NOT NULL,
`account_id` int(11) NOT NULL,
`status` enum('pending','complete') NOT NULL default 'pending',
`created_at` datetime NOT NULL,
`created_by` int(11) NOT NULL,
PRIMARY KEY (`id`),
KEY `fk_orders_users1` (`created_by`),
KEY `fk_orders_data1` (`data_id`),
KEY `fk_orders_accounts1` (`account_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
However when I look at the structure via phpmyadmin it lists the foreign key with the same name. Do I need to do something else before I can drop the foreign keys?
There are no foreign keys. Refer MySQL documentation which says
KEY is normally a synonym for INDEX.
So basically in table you have created indexes, not foreign keys. For Foreign Key info, Click here
You need to temporarily drop the constraint so that you can remove it.
SET FOREIGN_KEY_CHECKS=0;
and then turn them on again after you drop the foreign key:
SET FOREIGN_KEY_CHECKS=1;
first drop foreign key then delete column
alter table 'table name' drop foreign key 'constraint id ;
if you don't know constraint id create database dump in that constraint id is available in dump file ..
then delete column..
The index name and constraint name may not be same. You should delete constraint first using code: ALTER TABLE tablename DROP FOREIGN KEY constraintname
Here's my table:
CREATE TABLE `alums_alumphoto` (
`id` int(11) NOT NULL auto_increment,
`alum_id` int(11) NOT NULL,
`photo_id` int(11) default NULL,
`media_id` int(11) default NULL,
`updated` datetime NOT NULL,
PRIMARY KEY (`id`),
KEY `alums_alumphoto_alum_id` (`alum_id`),
KEY `alums_alumphoto_photo_id` (`photo_id`),
KEY `alums_alumphoto_media_id` (`media_id`),
CONSTRAINT `alums_alumphoto_ibfk_1` FOREIGN KEY (`media_id`) REFERENCES `media_mediaitem` (`id`),
CONSTRAINT `alum_id_refs_id_706915ea` FOREIGN KEY (`alum_id`) REFERENCES `alums_alum` (`id`),
CONSTRAINT `photo_id_refs_id_63282119` FOREIGN KEY (`photo_id`) REFERENCES `media_mediaitem` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=63 DEFAULT CHARSET=utf8
I want to delete the column photo_id, which presumably will also require deleting the foreign key constraint and the index.
The problem is that I get errors when I try to drop the column:
ERROR 1025 (HY000): Error on rename of '.\dbname\#sql-670_c5c' to '.\dbname\alums_alumphoto' (errno: 150)
... when I try to drop the index (same as above), and when I try to drop the foreign key constraint:
ERROR 1091 (42000): Can't DROP 'photo_id_refs_id_63282119'; check that column/key exists)
What order should I be doing all of this in? What precise commands should I be using?
Precisely, try this :
First drop the Foreign Key or Constraint :
ALTER TABLE `alums_alumphoto` DROP FOREIGN KEY `photo_id_refs_id_63282119`;
The previous command removes the Foreign Key Constraint on the column. Now you can drop the column photo_id (the index is removed by MySQL on dropping the column) :
ALTER TABLE `alums_alumphoto` DROP COLUMN `photo_id`;
Aternatively, you could combine these 2 operations into one :
ALTER TABLE `alums_alumphoto`
DROP FOREIGN KEY `photo_id_refs_id_63282119` ,
DROP COLUMN `photo_id`;
The sure thing is to make a duplicate table.
> CREATE TABLE alums_alumphoto_new LIKE alums_alumphoto;
> ALTER TABLE .... // Drop constraint
> ALTER TABLE .... // Drop KEY
> ALTER TABLE .... // Drop the column
> INSERT INTO alums_alumphoto_new (SELECT id, alum_id, photo_id, media_id, updated FROM alums_alumphoto);
> RENAME TABLE alums_alumphoto TO alums_alumphoto_old, alums_alumphoto_new TO alums_alumphoto;
If there's an error executing RENAME TABLE, some other tables might have foreign key constraints referencing this table, in which case this whole approach is stupid. :)
Try combining the DROP KEY and DROP FOREIGN KEY statements.
ALTER TABLE `alums_alumphoto`
DROP KEY KEY `alums_alumphoto_photo_id`,
DROP FOREIGN KEY `photo_id_refs_id_63282119`;
ALTER TABLE `alums_alumphoto`
DROP COLUMN `photo_id`;