How can I temporarily disable a foreign key constraint in MySQL?

Question

Is it possible to temporarily disable constraints in MySQL?

I have two Django models, each with a foreign key to the other one. Deleting instances of a model returns an error because of the foreign key constraint:

cursor.execute("DELETE FROM myapp_item WHERE n = %s", n) transaction.commit_unless_managed()  #a foreign key constraint fails here  cursor.execute("DELETE FROM myapp_style WHERE n = %s", n) transaction.commit_unless_managed() 

Is it possible to temporarily disable constraints and delete anyway?

Answer 1

Try DISABLE KEYS or

SET FOREIGN_KEY_CHECKS=0; 

Make sure to

SET FOREIGN_KEY_CHECKS=1; 

after.

Answer 2

To turn off foreign key constraint globally, do the following:

SET GLOBAL FOREIGN_KEY_CHECKS=0; 

and remember to set it back when you are done

SET GLOBAL FOREIGN_KEY_CHECKS=1; 

WARNING: You should only do this when you are doing single user mode maintenance. As it might resulted in data inconsistency. For example, it will be very helpful when you are uploading large amount of data using a mysqldump output.