Sql Deploy targets a development/deploy environment where each database change is scripted into a "change script" that brings the database to that level/version. Each change script represents one database version and they are executed from the "lowest" to the "highest" version sequentially. If the database is already at the version that particular change script is at, that script is skipped. You can bring the database to a required version by supplying all change scripts up to and including that version. It supports backups, transactions, baseline scripts, test data population...