A uniform model for temporal object-oriented databases

A temporal object-oriented model and query language that supports the modeling and manipulation of complex temporal or versioned objects is developed. The authors show that the approach not only provides a richer model than the relational for capturing the semantics of complex temporal objects, but also requires no special constructs in the query language. Consequently, the retrieval of temporal and non-temporal information is uniformly expressed. By allowing variables and quantifiers to range over time, can be formulated that require special operators in other languages. Temporal aggregation queries, which are not easily expressed in other models, are expressed using the same aggregation operators as for nontemporal data