Implementing direct manipulation query languages using an adequate data model

Human factors work in the areas of database use addresses the design of the user interface of interactive database applications as well as the design of the on-line interface of the database system itself. Some conceptual prerequisites of using direct manipulation in an on-line database interface are discussed. It will be shown that choosing an adequate data model is vital in investigating the application of this style of interaction in complex database environments requiring a high level of abstraction. As an example, an advanced data model is introduced. In this model, the semantics of operating directly on a graphical database interface is specified, possible ambiguities are revealed, and a way of implementing the interface in an existing (e.g. normalized relational) data-base environment is shown.