How do we implement an IS-A Relationship?

Question

We implement an One-to-Many relationship by adding one Table's PK, as FK to the other Table. We implement a Many-to-Many relationship by adding 2 Table's PKs to a third Table.

How do we implement an IS-A Relationship ?

The Entities are TECHNICIAN and ADMINISTRATIVE which both are EMPLOYEE. I could just use an extra field in the Table EMPLOYEE(id, name, surname, role, ...AdminFields..., ...TechFields...)

but i would like to explore the IS-A option.

EDIT: I did as Donnie suggested, but without the role field.

Answer 1

I did as Donnie suggested, but without the role field, because it complicates things. This is the final implementation:

DDL:

CREATE TABLE Employee ( ast VARCHAR(20) not null, firstname VARCHAR(200) not null, surname VARCHAR(200) not null, ... PRIMARY KEY(ast) );  CREATE TABLE Administrative ( employee_ast VARCHAR(20) not null REFERENCES Employee(ast), PRIMARY KEY(employee_ast) );  CREATE TABLE Technical ( employee_ast VARCHAR(20) not null REFERENCES Employee(ast), ... PRIMARY KEY(employee_ast) ); 

ER Diagram:

In this model there are no Employees of Generic Type. Here, an Employee can only be Administrative or Technical.