In this paper we describe a new data modeling language we call $O^{2}LDM$. $O^{2}LDM$ incorporates features from object-oriented and logic approaches. In $O^{2}LDM$ there is a rich collection of objects organized in a type hierarchy. It is possible to compose queries that involve field selection, function application and other constructs which transcend the usual, strictly syntactic, matching of PROLOG. We give the features of $O^{2}LDM$ and motivate its utility for conceptual modeling. We have a prototype implementation for the language, which we have written in ML. In this paper we describe an executable semantics of the deductive process used in the language. We work some examples to illustrate the expressive power of the language, and compare $O^{2}LDM$ to PROLOG.