I'm looking for the best way to modify schemas through the development >> QA >> production process in a repeatable manner. It must have a way to determine if accidently running a script again is benign or not allowed. The environment I have is MSSQL2K, SourceSafe for storing the scripts, and ant to push the script(s) to the next level. Specific questions:
1. Should each version update be contained in one script or many? (Unfortunately there are multiple people doing schema changes)
2. How can I set up Source Safe to allow ant to pull the correct script?

Thanks.

I have a method of controlling versions/projects in sql server at

www.nigelrivett.com
Administering SQL Server Release Control

It probably doesn't cover your problem explicitely but the idea should be clear.
I'm going to extend this when I get time.