Re: case gurus??

willyk_at_kbigate.stgt.sub.org (Willy Klotz) writes:

>shiao_at_stsci.edu writes in article <1993Sep3.103648.1_at_stsci.edu>:
>>
>>

[Stuff deleted]

>According to ORACLE, the implementation of super- and subtypes is not
>very good. My approach is to have nearly no supertypes, I use them only
>if I want to "group" some data. But then, I have no attributes in the supertype.
 

>Willy
   

   I've been doing the opposite. For example, I have a supertype    called employee with sub-types salesperson, purchasing agent, etc.

   All relationships go to the sub-types. For example, a salesperson    takes an order, an order is taken by a salesperson.

   In implementation, I implement only the supertype of employee. The    foreign keys then refer to the sub-type but using the primary key    of the super type.

   In ORDERS, I get a foreign key called: SALESPERSON_EMPLOYEE_ID    rather than the EMP_EMPLOYEE_ID which would have resulted with    relationships to the EMPLOYEE entity.

   One has to be careful about the relationships to the sub-types    and/or supertypes. When implementing, implement only the    supertype or all of the sub-types.

Rich Holowczak
Rutgers University
holowcza_at_andromeda.rutgers.edu Received on Sun Sep 12 1993 - 19:22:12 CEST