Re: How can I implement subtypes ?

From: Diana Tracy <bs794_at_cleveland.Freenet.Edu>
Date: 2 Feb 1994 17:25:36 GMT
Message-ID: <2ionmg$t85_at_usenet.INS.CWRU.Edu>

In a previous article, fassian_at_crpht.lu (Torsten Fassian) says:

>Hi,
>
>ORACLE CASE offers the possibility to define subtypes in its
>ER-diagrammer.
>
>What are the different possibilities to implement this concept in the
>database. What are the advantages/disadvantages of these solutions? Which
>solutions are well supported by the CASE?
>
>Regards,
>Torsten
>

CASE implements it in it's generated code by creating one table and adding a column called SUB_TYPE. That I guess is the standard way to implement subtypes. For instance:

---

	|			|
 EMPLOYEE		|	
	|			|
 --------------	|
	|  | SALESPERSON|	|
	|  --------------	|
	-------------------------

is implemented as a table with the columns   EMPNO
  any employee attributes
  SUB_TYPE
  any salesperson attributes

Hope that helps.

-- 
Diana Tracy, System Designer		-- Excitement, Adventure
bs794_at_cleveland.Freenet.Edu		-- and Really Wild Things

Received on Wed Feb 02 1994 - 18:25:36 CET