Ed Elliott shares some tips on load testing a database:
Testing database performance is hard and takes a great deal of work to probably not even do particularly well. Instead of thinking about how you can load test a database think about how you can drive the application.
For instance, if you have a web app then use JMeter to simulate load. If you have a “fat app”, then you might need to write some code to call specific workflows through the application.
Click through for good advice, particularly around what you should not do.