Every Time You UPDATE a Row, You're Deleting...

The Problem That Wouldn't Go Away Early in a project I was working on, a customer filed a billing dispute. Simple enough, except when we went to check what subscription plan they were on at the time of the charge, we couldn't tell. Our database only stored the current state. The plan had been upgraded twice since then. The old values were gone. We weren't doing anything unusual. We had created_at and updated_at columns like every other project. But those tell you when a row changed, not what it