Generalization in Access

[Luca]

Is it possible to represent a generalization (coming from an E-R chart) in
Microsoft Access, and how?? For example I have the "GUEST" class and two
sub-classes "GUEST-BUY" and "GUEST-SELL" (this generalization is complete
and dosjoint), how can I set the integrity referential contraints so that
any item in the sub-classes is linked with the main class by the primary
key? The class "GUEST" should own all the attributes and the counter
(primary key); the sub-classes should only have the counter (or an integer)
to refer to the main class.
I have to develop a project for the university so please help me!! Thank you
all!


Luca

 

[John Vinson]

Is it possible to represent a generalization (coming from an E-R chart) in
Microsoft Access, and how?? For example I have the "GUEST" class and two
sub-classes "GUEST-BUY" and "GUEST-SELL" (this generalization is complete
and dosjoint), how can I set the integrity referential contraints so that
any item in the sub-classes is linked with the main class by the primary
key? The class "GUEST" should own all the attributes and the counter
(primary key); the sub-classes should only have the counter (or an integer)
to refer to the main class.

Just create a unique Index on the Long Integer foreign key field in
the subclass tables, and create a Relationship to the primary key of
GUEST. Access will recognize it as a one to one relationship.