We introduce an online test system whose development was partially supported by Bildungsportal Sachsen. The system is successfully deployed in the computer science course of studies at the University of Leipzig. The system functions are accessible by a web interface. It can be used for lecture based training or private study. For database courses the system provides a SQL-Trainer modul which can be used to learn the query language SQL. We present the conception and realization of the system and report on past experiences and planned extensions.