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good god help access isa relationships

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  • 22-11-2003 11:11pm
    #1
    HaVoC
    Registered Users Posts: 261 ✭✭


    someone please help me

    ok heres my problem doing an oop project in java, its a year long thing now our database is due up in 2 weeks and we have identifed several "isa" realationships or heiriarchys in the spec.

    now can ms access support these and if so how ??? looked on the net couldn't find a scrap of info about it.

    ok so i have come up with a few options for myself:

    1). do it in access reguardless and implement it using sepaerate insert sql statement for each level of the heirarchy

    2)forget about "isa" relationships and just create a one level database in access

    3). start in a new database program i have never used and implement them any suggestion ? something that can be lerant quickly ???

    well any input would be cool


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    #2
    bonkey
    Registered Users Posts: 15,443 ✭✭✭✭bonkey


    Whats an isa relationship?

    jc


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    #3
    boo-boo
    Closed Accounts Posts: 94 ✭✭boo-boo


    by an "isA" relationship I guess you mean using inheritance - the short answer is no.
    Access is a relational database and doesn't support this oo feature. There are some oo databases but I have never used them . You could check out Suns' site for patterns based on mapping oo entities to relational databases. Its a pretty common problem as most of the db's don't support all oo features.


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    #4
    HaVoC
    Registered Users Posts: 261 ✭✭HaVoC


    boo-boo thanks well have a look at sun now.

    by isA i mean inheritance ya like customer is a person and credit customer is a customer and so on.

    Friend said i can import ms access into ms sql srever so might do that also he gave this which look promising

    http://www.postgresql.org/
    i'll get there hopefully :(


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    #5
    bonkey
    Registered Users Posts: 15,443 ✭✭✭✭bonkey


    Ahhh...and here was me thinking ISA was a TLA.

    None of hte other dbs you mention (AFAIK) support OO techniques such as inheritence either.

    Personally, I would create seperate tables for the various "inherited" classes. If you really want to have a "base class" representation, set it up as a view.

    e.g.

    I'd have a Customer table, and a CreditCustomer table, and a "Person" view derived from a union across the two tables. In otherwords...the DB is designed in the "opposite direction" to the objects, if you see what I mean.

    Oh yeah - Views aren't specifically implemented in Access. It'd be a SELECT-based Query there.

    jc


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    #6
    HaVoC
    Registered Users Posts: 261 ✭✭HaVoC


    the above link to the database support inheirtance in way, but i cant find an insert an iheirtance object example anywhere on the site, for the example i was on about i'd guess you would just do 2 inserts? an insert for ever level

    well its just a question if i can do it all in 2weeks then


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