The document discusses database version control and different approaches for managing schema changes over time. It describes using plain SQL patch files with a simple patching strategy of applying incremental changes. Other approaches include Phing with DB Deploy for automating patches, Liquibase for database-agnostic change management, Akrabat DB Schema Manager for Zend Framework, and Doctrine Migrations for projects using Doctrine ORM. Branches and merging changes across environments are also covered.