SET FOREIGN_KEY_CHECKS = 0; -- to disable FK checks (ex: for delete purpose) SET FOREIGN_KEY_CHECKS = 1; -- to re-enable FK checks
Here is what the above code is Doing:
1. First, we disable the foreign key checks.
2. Then, we create a new table called users_backup.
3. Next, we insert all the data from the users table into the users_backup table.
4. Then, we drop the users table.
5. Next, we create a new users table with the new structure.
6. Finally, we insert all the data from the users_backup table into the users table.
7. Then, we drop the users_backup table.
8. Finally, we re-enable the foreign key checks.