If you've ever been suspicious that your Oracle or MySQL database is not functioning correctly, then one way of verifying it is to test the load capacity. That's exactly what Transaction Generator does by enabling various verification tests. It basically has three main features - testing the performance, detecting bottlenecks in databases and tuning the application. It also features a few other minor tools too.
It works by using JDBC (Java DataBase Connectivity) to connect to the database so it will have to support JDBC to conduct the test. The program generates a load by sending a series of SQL statements to the database server which is registered as a transaction. You can choose two types of interface to control - an interactive command-line interface and a GUI based interface which is called TGC (TG Controller). I recommend the latter because if you're not familiar with databases, the command line will confuse you completely.
This is certainly useful if you have issues with your database load although be warned that if you don't know basics about Oracle or MySQL databases, you could end up quite lost as it's quite technical and the instructions are sketchy.