The issue of modeling and querying such temporal events has been the subject of research the database community in recent years. We present an formalism based on a new periodic temporal type called periodic element to model periodic events in temporal databases, and illustrate its suitability by extending the object-oriented query language QQL of $O_2$ with a temporal data type hierarchy with an implementation. The temporal extension to the language is achieved through a set of absolute and relative periodic types which have well-defined temporal operators/functions written in the form of methods. Periodic elements are capable of representing aperiodic, strictly-periodic, and partially-periodic absolute and relative events, and can be used for implementing calendars, scheduling and other temporal applications.