-- Fix inconsistent FK ON DELETE behavior on bulk_operations.performed_by and
-- ticket_templates.created_by
--
-- Every other user-reference FK in the schema (tickets.created_by/updated_by/
-- assigned_to, ticket_attachments.uploaded_by, ticket_dependencies.created_by,
-- recurring_tickets.created_by/assigned_to, api_keys.created_by, etc.) uses
-- ON DELETE SET NULL. These two had no ON DELETE clause at all, which
-- defaults to RESTRICT — so deleting a user who ever ran a bulk operation or
-- created a template hard-fails at the DB level instead of nulling the
-- reference, breaking the pattern used everywhere else and potentially
-- blocking legitimate user offboarding/cleanup.
--
-- bulk_operations.performed_by is NOT NULL today; it must become nullable to
-- support SET NULL, matching how every other SET NULL column in the schema
-- is defined.
--
-- Safe to re-run.

ALTER TABLE `bulk_operations`
    MODIFY COLUMN `performed_by` int(11) DEFAULT NULL;

ALTER TABLE `bulk_operations`
    DROP FOREIGN KEY IF EXISTS `bulk_operations_ibfk_1`;

ALTER TABLE `bulk_operations`
    ADD CONSTRAINT `bulk_operations_ibfk_1` FOREIGN KEY (`performed_by`) REFERENCES `users` (`user_id`) ON DELETE SET NULL;

ALTER TABLE `ticket_templates`
    DROP FOREIGN KEY IF EXISTS `ticket_templates_ibfk_1`;

ALTER TABLE `ticket_templates`
    ADD CONSTRAINT `ticket_templates_ibfk_1` FOREIGN KEY (`created_by`) REFERENCES `users` (`user_id`) ON DELETE SET NULL;