In this talk I will argue that existing techniques are not adequate to deal with tranformations involving semantic or object-oriented data models, and, in particular that there is a need to take account of the interactions between database transformations and constraints, and to allow for partial specifications of complex data objects.
I will describe a declarative language, _WOL_, based on Horn-clause logic, for specifying database transformations and constraints, and its implementation in a system called _Morphase_. The implementation takes transformations specifications in WOL and manipulates their clauses into a normal form which can then be translated into an underlying database programming language.
This work was done as part of a PhD thesis at the University of Pennsylvania, with advisors Susan Davidson and Peter Buneman.