Querying temporal clinical databases with different time granularities: the GCH-OSQL language.

There is a need for managing temporal clinical information given at different levels of granularity. Different time granularities are also needed in querying clinical databases. In this paper, we describe GCH-OSQL (Granular Clinical History--Object Structured Query Language), an object-oriented temporally-oriented extension of SQL. GCH-OSQL is based on an object-oriented temporal data model. It allows storage of clinical information at different and mixed granularities. GCH-OSQL deals with the valid time of clinical information. GCH-OSQL offers also a graphical user-interface. It guides different end users, from expert to naive, to formulate expressive and correct queries.