How to Change a Foreign Key field into a Dropdown List
In the Definer, you can change the Lookup Method attribute of a relationship from Lookup Page (the default) to Dropdown List or Radio. This results in the appropriate lookup functionality automatically.
In some cases, you want to implement dropdown list or radio button functionality for a field without making conceptual changes at relationship level. For example, when there exists a conceptual relationship, but you don't want to make changes at generic (Definer) level.
To implement dropdown list functionality, if there is a conceptual relationship:
The name of this DataSource usually starts with: Lookup.
The top area of the object tree now looks like this:
If you want to use radio buttons instead of a dropdown list, use RadioColumnControls instead of SelectColumnControls.
A drop-down list has an empty value if it is not linked to a database table, or if it is linked to a non-mandatory column.