-- Live database patch: allow invoices without an email address.
-- Run this against the application's live MySQL database.

ALTER TABLE `invoices`
    MODIFY COLUMN `email` VARCHAR(255) NULL;

-- Verification:
SHOW COLUMNS FROM `invoices` LIKE 'email';

-- Optional rollback (remove the leading -- only if every row has an email):
-- UPDATE `invoices` SET `email` = '' WHERE `email` IS NULL;
-- ALTER TABLE `invoices` MODIFY COLUMN `email` VARCHAR(255) NOT NULL;