Summary form only given. Within the framework of an object oriented database graphical query environment for casual end users, a view definition mechanism conceived for users who are expert in their application domain, but not necessarily computer specialists, is proposed. In this mechanism, the focus is on the strength of the graphical view definition language and on the conviviality of the user interface. The view definition language offers adaptation operations to the work context and restructuring operations on both attributes and classes that take into consideration the structure's nesting and inheritance of the database classes. The user interface conviviality is based on the graphical visualization of the portion of the database schema that represents the domain of interest for a user group, and on the use of the graphical language for view definition. To eliminate crossings between different links of the visualized composition hierarchy, a method for graphical visualization is introduced.