A subtype discriminator is the attribute in the supertype entity that is utilized to decide to which entity subtype the supertype occurrence is connected. A subtype discriminator in an EMPLOYEE supertype table can be EMP_TYPE and it can hold a value F which is related to FACULTY subtype.
Overlapping subtypes will be subtypes which comprise of non-unique subsets of the supertype entity set. Example of an overlapping subtypes is classifying a high school employees as teachers or administrators since some teachers have likelihood of being an administrators.
Overlapping subtypes will be subtypes which comprise of non-unique subsets of the supertype entity set. Example of an overlapping subtypes is classifying a high school employees as teachers or administrators since some teachers have likelihood of being an administrators.