Let's create another doctype: Library Membership. It will have the following fields:
It will have Is Submittable enabled. It will have Naming set as
LMS.##### and restricted to Librarian role. Also, the Title Field should
be set to
full_name in the View Settings section.
The Link field Library Member is similar to a Foreign Key column in other frameworks. It will let you link the value to a record in another DocType. In this case, it links to a record of Library Member DocType.
The Full Name field is a Read Only field that will be automatically fetched
from from the
full_name field in the linked record Library Member.
Now, go to the Library Membership list and create a new document. You will see that the Library Member field is a dropdown with existing records shown as options. Select a Library Member and the Full Name will be fetched automatically. Pretty cool, right?