This paper presents a semantic model and processing language upon which a logical database design tool can be based. The semantic model is invariant with respect to the placement of data items into records or relations. The processing language is based on the semantic model, so processing specifications are also invariant to these decisions. This allows a designer to specify the processing and semantics of small parts of a database (local views), and then to integrate these views into a global model of the database. We present operations to manipulate the model and processing specifications during the integration process. An algorithm using these operations is given to perform the integration process.