Results 1 to 6 of 6
  1. #1
    Join Date
    Jun 2009
    Posts
    22

    Generalization and agregation

    How genralizationa and aggregation in ER Diagram to a physical RDBMS. Can any body have some example of such a scenario?

  2. #2
    Join Date
    Apr 2002
    Location
    Toronto, Canada
    Posts
    20,002
    Quote Originally Posted by sayyed_kamran View Post
    How genralizationa and aggregation in ER Diagram
    there are some good resources here --> generalization and aggregation in ER diagram

    rudy.ca | @rudydotca
    Buy my SitePoint book: Simply SQL

  3. #3
    Join Date
    Jun 2009
    Posts
    22
    Thnks r937:

    Here is my origional problem:

    I am going to develope a Help DesK, The user will raise a ticket by selecting some predefind set of services like:

    1. Software Maintinance
    2. Office equipment Maintinance
    3. Newtwork Problem etc etc

    I have a table like the following:

    ServcieId,
    ParentServiceID,
    ServcieName,
    ServcieProvidingArea
    etc etc

    Now my problem is there are varying needs of each and every service category like:

    If the user selected Networ services , he must mention whether the problme is in WAN, Lan or Ring0 Network. (We call this attribute as Network Type)

    If the user select PHOTOCOPIER MAINTINANCE he/she will have to mention
    COUNTER (a number that indicates the number of copies done by the photocopier till date )

    now the problem i here is that we do the service Netowrk Problem has nothing to do with COUNTER and similarly the Service Photocopier maintinance has nothing to do with Networ Type.

    This situation gives me the idea that I should user Generalization/Specialization etc.

    1. Am I right in guessing that this is a problem to be solved using Generalization/Specialization?

    2. If yes then how to apply Generalization/Aggregation to this problem , If No what is the physible solotuion to the problem
    Last edited by sayyed_kamran; 12-24-10 at 06:57.

  4. #4
    Join Date
    Apr 2002
    Location
    Toronto, Canada
    Posts
    20,002
    Quote Originally Posted by sayyed_kamran View Post
    1. Am I write in guessing that this is a problem to be solved using Generalization/Specialization?
    yes

    see http://www.dbforums.com/oracle/16587...ml#post6471590
    rudy.ca | @rudydotca
    Buy my SitePoint book: Simply SQL

  5. #5
    Join Date
    Jun 2009
    Posts
    22
    Is there some other elagent solution then the one given there? My study/Research shows that this is a problem of Specialization but I cant understand how to solve it with Specialization.

  6. #6
    Join Date
    Apr 2002
    Location
    Toronto, Canada
    Posts
    20,002
    that ~is~ an elegant solution

    the service type table is the generalization (supertype), and the various detailed service tables are the specializations (subtypes)
    rudy.ca | @rudydotca
    Buy my SitePoint book: Simply SQL

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •