MySQL: how to ignore checking of foreign key constraints for InnoDB tables

Posted October 3, 2008 * Comments(13)

There is a session variable FOREIGN_KEY_CHECKS which allows to ignore checking of foreign key constraints for InnoDB tables.

If set to 1 (the default), foreign constraints are checked. If set to 0, they are ignored.
Setting FOREIGN_KEY_CHECKS to 0 also affects data definition statements like DROP TABLE which drops tables that have foreign keys that are referred to by other tables.

Disabling foreign key checking can be useful for reloading InnoDB tables in an order different from that required by their parent/child relationships.

Using session variables:

SET FOREIGN_KEY_CHECKS = 0;
 
SELECT @@FOREIGN_KEY_CHECKS;
 
SET FOREIGN_KEY_CHECKS = 1;

13 Comments so far

  1. Joao on October 19th, 2009

    Thank you, I was just looking for this.

  2. Abc on February 17th, 2010

    Thank you my collegues were looking for this for 2 hours :D and now they say it is team work! peh

  3. gx on July 5th, 2010

    thank you, nice post :)

  4. Darren L on October 5th, 2010

    Thanks this helped out.

  5. Didier on December 12th, 2010

    Thanks, this helped a lit (again).

  6. Jstall on March 30th, 2011

    Thanks much for this, don’t know why I didn’t look for a solution like this sooner.

  7. Viktor on August 13th, 2011

    Can it also be used in case you want to delete records with check

  8. Alex on August 15th, 2011

    Viktor,

    Yes, it is possible to do something like this:

    SET FOREIGN_KEY_CHECKS = 0;
    DELETE FROM `t`;
    SET FOREIGN_KEY_CHECKS = 1;

    Also depending on your application needs you may want to consider setting foreign_key_checks = 0 permanently in the MySQL configuration file.

  9. Naveen on September 21st, 2011

    Thanks Alex! This is what I wanted.

  10. Erik on June 26th, 2012

    Thanks, great help.

  11. Jaime de la Torre on December 28th, 2012

    Thanks a lot from Mexico City

  12. senthilvel on March 22nd, 2013

    Can I use this, while importing into a child table?

  13. Alex on March 29th, 2013

    Yes, there are no restrictions from the technical point of view.

Leave a reply