Yes patches are typically sql scripts to migrate user data when for example the database schema changes or is refactored with version upgrades.
Here is a case of the bench run-patch command V12 Upgrade Issue: DocType Item Manufacturer not found
Yes patches are typically sql scripts to migrate user data when for example the database schema changes or is refactored with version upgrades.
Here is a case of the bench run-patch command V12 Upgrade Issue: DocType Item Manufacturer not found