In order to set any field as **mandatory** during execution, then I could create a **selection view** on top of the base view with View parameter. The value of the View parameter can be assigned to the existing field of the selection view from the WHERE CONDITION tab.
To get more information, you can refer to the [Parameters of Derived Views](https://community.denodo.com/docs/html/browse/8.0/en/vdp/administration/creating_derived_views/creating_selection_views/creating_selection_views#parameters-of-derived-views) section of the Virtual DataPort Administration Guide.
Alternatively, you can also **edit** the VQL code associated with the **base view** in order to change to the field as mandatory.
Hope this helps!