I am trying to temporarily disable foreign key checks, but have not been successful.
```
SET FOREIGN_KEY_CHECKS=0;
DROP TABLE IF EXISTS `menu_items`;
CREATE TABLE `menu_items` (
...
SET FOREIGN_KEY_CHECKS = 1;
```
It keeps telling me that I cannot delete or update a parent row. Any help would be appreciated!
To disable foreign key constraints when you want to truncate a table:
Use FOREIGN_KEY_CHECKS
SET FOREIGN_KEY_CHECKS=0;
Or you can use DISABLE KEYS:
ALTER TABLE table_name DISABLE KEYS;
Related
I know you can disable foreign key check by set 0 to the FOREIGN_KEY_CHECKS, but in mysql BD with phpmyadmin Version 4.8.5, it does not work for me.
I want to drop the table without checking foreign key constraint
SET FOREIGN_KEY_CHECKS=0;
DROP TABLE IF EXISTS table_name;
SET FOREIGN_KEY_CHECKS=1;
I expect the query to drop the table, but I got this error.
Cannot delete or update a parent row: a foreign key constraint fails
What could be a possible solution?
So I'm trying to run this command:
ALTER TABLE user MODIFY COLUMN email VARCHAR(100) UNIQUE;
but it gives me this error,
Cannot delete rows from table which is parent in a foreign key constraint 'draft_map_ibfk_1' of table 'draft_map'
There are no duplicates in the table, so it shouldn't be deleting anything. The email column is currently a TEXT, so is that what's causing the issue?
Temporary disable foreign hey checks:
SET foreign_key_checks = 0;
To enable it back use:
SET foreign_key_checks = 1;
I would like to DROP and create back the same table in using phpmyadmin.
DROP TABLE IF EXISTS `product_entity`;
CREATE TABLE `product_entity` ( ...... );
I get error message
Cannot delete or update a parent row: a foreign key constraint fails
Then I set
SET FOREIGN_KEY_CHECKS=0;
DROP TABLE IF EXISTS `product_entity`;
SET FOREIGN_KEY_CHECKS=1;
CREATE TABLE `product_entity` ( ...... );
My question is how to verify that SET FOREIGN KEY CHECKS is set to = 1?
Thanks.
Try this in console
SELECT ##foreign_key_checks;
See Demo
Try this in console
show variables like 'fo%'
http://sqlfiddle.com/#!2/d41d8/29738
In MySQL I want to drop a table.
I tried a lot things but I keep getting the error that the table named bericht can't be dropped. This is the error I'm getting:
#1217 - Cannot delete or update a parent row: a foreign key constraint fails
How do I drop this table?
This should do the trick:
SET FOREIGN_KEY_CHECKS=0; DROP TABLE bericht; SET FOREIGN_KEY_CHECKS=1;
As others point out, this is almost never what you want, even though it's whats asked in the question. A more safe solution is to delete the tables depending on bericht before deleting bericht. See CloudyMarble answer on how to do that. I use bash and the method in my post to drop all tables in a database when I don't want to or can't delete and recreate the database itself.
The #1217 error happens when other tables has foreign key constraints to the table you are trying to delete and you are using the InnoDB database engine. This solution temporarily disables checking the restraints and then re-enables them. Read the documentation for more. Be sure to delete foreign key restraints and fields in tables depending on bericht, otherwise you might leave your database in a broken state.
Try this:
SELECT *
FROM information_schema.KEY_COLUMN_USAGE
WHERE REFERENCED_TABLE_NAME = 'YourTable';
This should deliver you which Tables have references to the table you want to drop, once you drop these references, or the datasets which reference datasets in this table you will be able to drop the table
But fortunately, with the MySQL FOREIGN_KEY_CHECKS variable, you don't have to worry about the order of your DROP TABLE statements at all, and you can write them in any order you like -- even the exact opposite -- like this:
SET FOREIGN_KEY_CHECKS = 0;
drop table if exists customers;
drop table if exists orders;
drop table if exists order_details;
SET FOREIGN_KEY_CHECKS = 1;
For more clarification, check out the link below:
http://alvinalexander.com/blog/post/mysql/drop-mysql-tables-in-any-order-foreign-keys/
Use show create table tbl_name to view the foreign keys
You can use this syntax to drop a foreign key:
ALTER TABLE tbl_name DROP FOREIGN KEY fk_symbol
There's also more information here (see Frank Vanderhallen post):
http://dev.mysql.com/doc/refman/5.5/en/innodb-foreign-key-constraints.html
This probably has the same table to other schema the reason why you're getting that error.
You need to drop first the child row then the parent row.
I realize this is stale for a while and an answer had been selected, but how about the alternative to allow the foreign key to be NULL and then choose ON DELETE SET NULL.
Basically, your table should be changed like so:
ALTER TABLE 'bericht'
DROP FOREIGN KEY 'your_foreign_key';
ALTER TABLE 'bericht'
ADD CONSTRAINT 'your_foreign_key' FOREIGN KEY ('column_foreign_key') REFERENCES 'other_table' ('column_parent_key') ON UPDATE CASCADE ON DELETE SET NULL;
Personally I would recommend using both "ON UPDATE CASCADE" as well as "ON DELETE SET NULL" to avoid unnecessary complications, however your set up may dictate a different approach.
Hope this helps.
I get this error message:
ERROR 1217 (23000) at line 40: Cannot
delete or update a parent row: a
foreign key constraint fails
... when I try to drop a table:
DROP TABLE IF EXISTS `area`;
... defined like this:
CREATE TABLE `area` (
`area_id` char(3) COLLATE utf8_spanish_ci NOT NULL,
`nombre_area` varchar(30) COLLATE utf8_spanish_ci NOT NULL,
`descripcion_area` varchar(100) COLLATE utf8_spanish_ci NOT NULL,
PRIMARY KEY (`area_id`),
UNIQUE KEY `nombre_area_UNIQUE` (`nombre_area`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_spanish_ci;
The funny thing is that I already dropped all other tables in the schema that have foreign keys against area. Actually, the database is empty except for the area table.
How can it possibly have child rows if there isn't any other object in the database? As far as I know, InnoDB doesn't allow foreign keys on other schemas, does it?
(I can even run a RENAME TABLE area TO something_else command :-?)
On demand, now as an answer...
When using MySQL Query Browser or phpMyAdmin, it appears that a new connection is opened for each query (bugs.mysql.com/bug.php?id=8280), making it neccessary to write all the drop statements in one query, eg.
SET FOREIGN_KEY_CHECKS=0;
DROP TABLE my_first_table_to_drop;
DROP TABLE my_second_table_to_drop;
SET FOREIGN_KEY_CHECKS=1;
Where the SET FOREIGN_KEY_CHECKS=1 serves as an extra security measure...
Two possibilities:
There is a table within another schema ("database" in mysql terminology) which has a FK reference
The innodb internal data dictionary is out of sync with the mysql one.
You can see which table it was (one of them, anyway) by doing a "SHOW ENGINE INNODB STATUS" after the drop fails.
If it turns out to be the latter case, I'd dump and restore the whole server if you can.
MySQL 5.1 and above will give you the name of the table with the FK in the error message.
Disable foreign key checking
SET FOREIGN_KEY_CHECKS=0
from this blog:
You can temporarily disable foreign key checks:
SET FOREIGN_KEY_CHECKS=0;
Just be sure to restore them once you’re done messing around:
SET FOREIGN_KEY_CHECKS=1;
hopefully its work
SET foreign_key_checks = 0;
DROP TABLE table name;
SET foreign_key_checks = 1;
On Rails, one can do the following using the rails console:
connection = ActiveRecord::Base.connection
connection.execute("SET FOREIGN_KEY_CHECKS=0;")
Maybe you received an error when working with this table before. You can rename the table and try to remove it again.
ALTER TABLE `area` RENAME TO `area2`;
DROP TABLE IF EXISTS `area2`;
i found an easy solution, export the database, edit it what you want to edit in a text editor, then import it. Done
Cannot delete or update a parent row: a foreign key constraint fails (table1.user_role, CONSTRAINT FK143BF46A8dsfsfds##5A6BD60 FOREIGN KEY (user_id) REFERENCES user (id))
What i did in two simple steps . first i delete the child row in child table like
mysql> delete from table2 where role_id = 2 && user_id =20;
Query OK, 1 row affected (0.10 sec)
and second step as deleting the parent
delete from table1 where id = 20;
Query OK, 1 row affected (0.12 sec)
By this i solve the Problem which means Delete Child then Delete parent
i Hope You got it. :)