How to Temporarily Disable Foreign Key Constraints in MySQL for Data Manipulation?

Disabling Foreign Key Constraints in MySQL for Temporary Data Manipulation

In MySQL, foreign key constraints ensure data integrity by preventing inconsistencies in relationships between tables. However, these constraints can sometimes hinder quick data manipulations.

Problem:

When deleting instances of a model in Django, errors may occur due to foreign key constraints. For instance:

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()

Solution:

To temporarily disable foreign key constraints and allow deletions, you can use either the DISABLE KEYS command or set the FOREIGN_KEY_CHECKS variable to 0.

Using DISABLE KEYS:

DISABLE KEYS

This command disables all foreign key constraints for the current session.

Using SET FOREIGN_KEY_CHECKS variable:

SET FOREIGN_KEY_CHECKS=0;

This command sets the global FOREIGN_KEY_CHECKS variable to 0, disabling all foreign key constraints.

Important: After performing the desired data manipulation, remember to re-enable the foreign key constraints by setting FOREIGN_KEY_CHECKS back to 1:

SET FOREIGN_KEY_CHECKS=1;

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