Modern database applications require advanced means for modelling system structure and dynamics. Temporal logic has been proven to be a suitable vehicle for specifying the possible evolution of objects to be stored in databases. Past-directed temporal logic, as a means to describe the influence of the historical evolution of a database on applicable state changes, is one facet for the specification of object behaviour. The conceptual modelling language \tt TROLL emphasizes the behaviour of objects over the course of time. Especially the restriction of events with preconditions in past-directed temporal logic has to be monitored, when a system specified in \tt TROLL is implemented or prototyped. In this report we introduce a technique for monitoring (past-directed) temporal preconditions during database runtime. This technique avoids storing the whole database history for evaluating temporal preconditions.