Class diagrams must be complemented with a set of system operations that describes how users can modify and evolve the system state. To be useful, such a set must be complete (i.e. through these operations, users should be able to modify the population of all elements in the class diagram) and executable (i.e. for each operation, there must exist a system state over which the operation can be successfully applied). Manual specification of these operations is an error-prone and time-consuming activity. Therefore, the goal of this paper is to automatically provide a basic set of system operations that verify these two properties. Operations are drawn from the elements (classes, attributes, etc) of the class diagram and take into account the possible dependencies between the different change events (i.e. inserts/updates/deletes) that may be applied to them. Afterwards, the designer could reuse our proposal to build up more complex operations.