In this paper we describe a method to perform type inference over data stored in an RDBMS, where rules over the data are specified using OWLDL. Since OWL-DL is an implementation of the Description Logic (DL) called SHOIN(D), we are in effect implementing a method for SHOIN(D) reasoning in relational databases. Reasoning may be broken down into two processes of classification and type inference. Classification may be performed efficiently by a number of existing reasoners, and since classification alters the schema, it need only be performed once for any given relational schema as a preprocessor of the schema before creation of a database schema. However, type inference needs to be performed for each data value added to the database, and hence needs to be more tightly coupled with the database system. We propose a technique to meet this requirement based on the use of triggers, which is the first technique to fully implement SHOIN(D) as part of normal transaction processing.