Supporting the design of conceptual schemata by database systems

Designing the conceptual schema of databases is mainly a task of understanding the application world rather than applying a data model to specific situations. In spite of making use of formal terms like functional dependencies, relations etc. experiences in consulting show that a design process should reflect a learning situation and has to start with comprehensible, simplest (i.e. elementary) sentences. A strict constructive approach is outlined guaranteeing that new complex sentences can only be introduced by means of sentences already available to the designer. The structure of the metadatabase is outlined and an implemented design system is described.