When doing Performance Testing or running Unit/Functional tests on a database, there is a need to periodically get the database to a known state, so that the tests behave in a predictable way and to get rid of all the data created by the tests. Some of the ways to get a clean database are.
Using Scripts: Recreate the database using scripts, the same scripts that are used in development environment.
Using DB Backup: Especially when the database (and the data set) is large (using the scripts approach above will be slow) is to make a backup of the database in its pristine state and then run the tests, once the tests are done running, restore the database with the backup that was done before the tests corrupted the data.
Using Virtual Machine: The DB backup approach can be improved by using Virtual Machine (VM). Setup a VM and run the database server inside the VM, get the database and data so that the tests can run. Now make a image of the VM and run the tests, when the tests are done all that needs to be done is to restore the image of the VM.