Re: E/R questions

 You have a many to many zipcode relationship. The model becomes
:
: .----------. from .-----------------.
: | zip code |-----<| | Enitiy will have
: | city | zip | table will have | distance
: | | | from_zip, |
: | | to | to_zip. |
: | |-----<| distance |
: `----------' zip `-----------------'
:
:
 Jay Krishnamurthy (jkrish_at_lpp.sdi.agate.net) wrote:
: I have an entity that contains zip code and city.
 

: I would like to establish another entity called distance that contains
: "From zip", "To zip" and "distance". Any ideas on how to represent this
: in an Designer/2000 E/R diagram?
 

: Should distance be a sub-type within zip, and have a recursive (pig's
: ear) relationship to itself? i.e.
: ZIP
: -------------------------
: | zip code |
: | city |
: | |
: | -------------- |
: | |distance | |
: | ------------- |
: |-----------------------|
 

: The sub-type has a recursive relationship to itself. Is this valid?
 

: Or is there a better way to represent this?
 

: Thanks.

--
This posting represents the personal opinions of the author. It is not the
official opinion or policy of the author's employer. Warranty expired when you
opened this article and I will not be responsible for its contents or use.