Does anybody understand how to do wise database update in realtime.

E.g. I've got a site having a great database. All of a sudden I have made some code changes and database structure and data changes. Can there be any standard expect to do it with deploy script or any deploy soft? In realtime without preventing the website?

E.g. switch between two clone databases or smth like this. How can experienced people do this?

Website is designed in php, database is MySql.

Thanks!

Perhaps you have checked out DBdeploy? There is a good article here on controlling database deployments using Phing and DBdeploy

Red-colored Gate MySQL Compare includes a 14-day completely functional trial. It preserves data when you are performing schema changes. There's additionally a separate MySQL Data Compare tool.

http://www.red-gate.com/products/sql-development/mysql-compare/