My current client has a reasonably rigourous process. Database changes go to a review board with business and technical people who have been developing the system for decades. Once coded it is peer reviewed, deployed and tested in a minimal way then deployed and system tested. It also is deployed and tested in a "like production" environment and finally in production it is tested by end users before accepting the release.

Automated tests and scripted deployments are essential to ensure an efficient release process. All automated deployments are launched manually following receipt of approval.