On the Quality Assurance in PHP Projects site, Mike Lively has written up a few thoughts on how developers and development environments should work with testing databases as resources (case study).
Proper interaction with relational databases is incredibly important in most pieces of software. The importance of this interaction is underscored by the fact that many software architectures have at least one entire layer or system devoted to data persistence and data loading. When dealing with critical data in enterprise level applications it becomes even more important to make sure your data is being stored and retrieved correctly.
He talks about a case study on the topic (still in development) that will talk about testing techniques, functionality and how to create the tests needed to ensure your development environment can correctly use the database resource via unit tests and functional tests.