UPDATE scheduled_notifications
SET status = 'cancelled', cancelled_at = CURRENT_TIMESTAMP, updated_at = CURRENT_TIMESTAMP
WHERE channel = 'in_app' AND status IN ('pending', 'processing');

ALTER TABLE scheduled_notifications
    DROP CONSTRAINT IF EXISTS scheduled_notifications_channel_check;

ALTER TABLE scheduled_notifications
    ADD CONSTRAINT scheduled_notifications_channel_check
    CHECK (channel IN ('email', 'sms', 'push'));